This is the

Cumulus 1 FAQ

(consult also the Help screens within Cumulus software, and learn more from the rest of this Wiki)

A separate FAQ was created specifically for Cumulus MX FAQ

Installing and Running Cumulus

What operating systems does Cumulus run on?

Cumulus 1 - All versions of Windows from XP to Windows 11 inclusive (and the server versions). It works on 32 bit and 64 bit editions.

Where do I find the Cumulus 1 installer?

All available via the Downloads page in this Wiki

What do I need to get right when first getting Cumulus 1?

The installation process for Cumulus 1 displays readme.txt, that has many tips. See also Setup. Below are three key points.

  1. Install Cumulus in its own directory directly under a drive root.
  2. Connect your weather station before you start Cumulus
  3. When you first run Cumulus 1, it displays the Station settings screen. On this, make sure you pick the right sort of station (to ensure Cumulus communicates correctly with your weather station, and can identify all the observations) and choose your units wisely. (Changing units later means all stored Lowest and highest numbers up to that point have to be converted immediately manually). See the Help for information about the rest of the screen, but generally you can easily adjust the other options later.

What weather stations does Cumulus 1 work with?

 Reminder, this FAQ answer is ONLY for Cumulus 1

  • Davis Vantage Pro (VP), Vantage Pro2 (VP2), and Vue (the Envoy8X and Weatherlink Live is not supported).
  • Oregon Scientific WM918, WMR918, WMR928, WMR968, WMR88 (see this FAQ), WMR100, WMR180, WMR200.
  • Fine Offset - USB-connected stations which use the Easyweather software such as MyDEL, Nevada, Watson and Fine Offset, with model numbers such as WH1080, WH1081, W8681, 265NC etc.
  • La Crosse WS2300 range (see this FAQ). You may have problems with corrupt data if you use a WS23xx with a serial/USB adapter; this combination is therefore not supported.

For a more complete list see the Supported Devices page.

Will you support a new weather station type?

 Reminder, this FAQ answer is ONLY for Cumulus 1

Cumulus 1 is no longer being developed, its source code is no longer available, so it cannot be edited to support anything new.

How do I get Cumulus to update to the internet?

 Reminder, this FAQ answer is ONLY for Cumulus 1

Cumulus 1 provides multiple options:

  • Internet Update - this feature is to place web pages onto a personal web server. You can use the web templates provided with Cumulus, or your own (customised) pages. This is optional, and there are a lot of settings to get right, but it is a standard feature that has always been part of Cumulus.
  • APRS/CWOP - this feature is to update your observations onto the server, the update will happen automatically while Cumulus is running if you configure it in the APRS/CWOP frame within Cumulus internet settings.
  • Weather Underground - this feature is to update your observations onto the weather underground web pages, the update will happen automatically while Cumulus is running if you configure it in the weather underground frame within Cumulus internet settings.
  • PWS Weather/WeatherForYou/HAMweather - this feature is to update your observations onto these systems, the update will happen automatically while Cumulus is running if you configure it in the PWS weather frame within Cumulus internet settings.
  • Weatherbug - this feature is to update your observations onto Weatherbug, the update will happen automatically while Cumulus is running if you configure it in the Weatherbug frame within Cumulus internet settings.
  • WOW - this feature is to update your observations onto UK Met Office Weather Observations Website, the update will happen automatically while Cumulus is running if you configure it in the WOW frame within Cumulus internet settings.
  • Twitter - this feature allows you to send a message to at an interval that you configure in the twitter frame within Cumulus internet settings.

How do I request a new feature for Cumulus 1

 Reminder, this FAQ answer is ONLY for Cumulus 1

As of 2017, development of Cumulus 1 was stopped by Steve Loft and a new version called Cumulus MX beta replaced it. Although there have been a couple of patches to change the years listed in drop downs with Cumulus 1, its code is frozen as the relevant development environment is no longer available.

Consequently, there is no possibility of any new features for Cumulus 1.

Why haven't you added the feature I asked for a long time ago?

 Reminder, this FAQ answer is ONLY for Cumulus 1

Steve Loft developed and supported Cumulus in his spare time while having a full time job. He invited donations, but didn't make a living from Cumulus. He added facilities when he could. There was a long list of enhancement requests but many were not implemented and the list was lost during a move between hosts. Thus any feature requested in that list, which has not been implemented since, will not be implemented.

How do I upgrade to a new Cumulus 1 release?

  There are no upgrades available for Cumulus 1.

If you are using an earlier version of Cumulus 1, do upgrade now,

  1. first download the installer CumulusSetup.exe from (Downloads/CumulusSetup.exe).
  2. Next follow the instructions at Setup page
  3. Finally, replace just the one file "Cumulus.exe" in your installation by the patch available from Downloads page.

If you are using the final version of Cumulus 1, and your drop down dates do not run to 2030, then you need to follow this last instruction and apply the patch

Do I need to leave Cumulus running all the time

This answer applies to all flavours of Cumulus.

Cumulus is designed on the basis that it works best if it is operating continuously, so it can interrogate the weather station at maximum frequency and has least risk of missing extreme measurements. All the derived calculations (maximum and minimum in a day, apparent temperature, average temperature,and many more will be more accurately calculated if based on the most possible measurements at consistent intervals.

if you are using the EasyWeather input option or your weather station does not have a logger, then Cumulus must run all the time, because there is no way of accessing readings while it is 'switched off'.

That said, many Cumulus users do turn their devices off when they are not around, to save energy or reduce fire risk; and accept that the quality of the derivatives output is poorer and that some extremes may be missed, some averages might be biased etc. When Cumulus is restarted, if the weather station it is talking to has retained measurements in a logger, Cumulus will read these, and do a catch-up from when you turned it off (it may miss some if the clocks have changed, see later question). Cumulus will roll over to next day when it has finished reading logger results from previous day and starts with those to assign to new day.

Changing to different weather station

 Reminder, this FAQ answer is ONLY for Cumulus 1

Just change the station type. If Cumulus doesn't start reading the data from the new station, stop Cumulus and start it again. Some of the rain figures may be odd for a while (e.g. rain in last 24 hours). It is as simple as that.

In testing planned changes to Cumulus, I switch backwards and forwards between a Fine Offset and a WMR200 frequently, the only thing that happens is that the rain figures go wrong initially (because the two stations have different counters).

Moving Cumulus software to a new PC (or updating Windows Operating System)

 Reminder, this FAQ answer is ONLY for Cumulus 1

Cumulus will continue to work with your existing weather station and existing log files, providing

  1. Your Windows regional settings are the same (i.e. date format unchanged, same time zone, decimal point symbol unchanged, list separator character unchanged) - if there is a difference, the new installation cannot understand the old lines in the log files and will give an error when Cumulus is restarted.
  2. You may need to 'tweak' a few things (serial port number etc) in cumulus.ini.
  3. In the folder with cumulus.exe in it, copy across 'cumulus.ini', and if you have created a 'strings.ini' that file must be copied across too.
  4. The Cumulus 'data' sub-folder has been copied across.
  5. Obviously if you use customised web pages, then you need the corresponding templates in the new installation.
  6. Any other customised files (images and/or a twitter.txt file, for example), you may want to copy those over too.

Can I view my Cumulus data on another device?

 Reminder, this FAQ answer is ONLY for Cumulus 1

  1. If Cumulus uploads your weather information to an online web site, you can view that on another device.
  2. Software like 'Remote Desktop' can be used to view the computer that is running Cumulus - see many postings on the Support Forum.
  3. A back-up as described in the next answer can be viewed in Cumulus installed on another PC (see point about Windows regional settings in previous question) to look at past extremes or graphs; although obviously that additional installation will not be able to add further observations from the weather station connected to the original PC.
  4. If your web site is on your local network, but not online, your device may be able to view it directly or view a back-up of how it was in the past.

How do I back up my data?

 Reminder, this FAQ answer is ONLY for Cumulus 1

Recent builds of Cumulus 1 back up some of the log files each time the software is restarted in the backup folder and each time it processes a rollover it stores the log files as they are at the start of a new day in the daily folder. The routine that does this ensures no more than 7 sub-folders are kept in each of those main folders. These back up are designed to help you restart Cumulus 1 in the event of a problem they are not not preserving your valuable data.

Consequently you are advised to make your own arrangements for ensuring you do not lose your data.

  • Copy the contents of the Cumulus ‘data’ sub-folder on a regular basis to a different storage device. Then if you have any problem with the original storage device, or corruption of files, you can minimise the loss of logged observations. To restore from the backup, just copy the saved data folder back into your Cumulus installation, with Cumulus stopped.
  • It can be useful to take copies of the Cumulus 'backup' sub-folder on key dates (e.g. at change of month or year), or if you think you might have some rogue figures. The '.ini' files in the backup sub-folder contain past extreme values that you might want to look up.
  • You should also back up, at least once, your cumulus.ini file in the main Cumulus folder. This contains all the key settings and you need a record of those!

Moving Cumulus 1 software to a different location on your PC?

 This article in the wiki gives more details above moving Cumulus: Moving cumulus

What are the formats of the Cumulus data files?

These are detailed in the Log Files section of this Wiki, see that category page for key information about log files and the content.

Format information is also in the Cumulus 1 help file, in the section “Data log file format”

Can I import logged information from before I installed Cumulus?

The Configuration menu, Station setting screen (near bottom) has option to enter there the rainfall total for the bit of the year (starting month can be selected here too) until when you first start using Cumulus. See the Cumulus Help for this screen for further details.

Yes is the answer for other weather information, providing you can manipulate the information you have into either (preferably) the format used by the Standard_log_files#Importing_pre-Cumulus_data or (second best) Dayfile.txt. Look up those cross-references in this Wiki (or the Cumulus Help) for further information on required formats. The support forum includes a few threads related to this topic, and if you post there then people who have already imported from particular systems may offer their services to import your past observations.

A converter for Weather Display log files is available from software page

A converter for WeatherLink log files is available from Software page

I was away on the last day of last month/year - How do I see the final lowest and highest figures for last month/year?

  View menu, This month or This year screens show some figures for any month or year selected by you, but do not show all the figures shown on a standard web page or as shown on the Highs and Lows screen for the current month/year.

View menu, Highs and Lows - This month (or This year) (or thismonth.htm or thisyear.htm web page) only shows the lowest and highest values for the current calendar month (or current year). This answer describes a way to see the same information for the month (or year) that fairly recently ended. It is valid only until build 1088 (from 5 March 2014 build 1089 'Delay writing of end of day backup files until the first log entry is written' means the stored month.ini relates to the initial entries for the start of the new month). From version 1.9.3 build 1041, Cumulus creates a daily backup of the log files.

  • Look in the backup\daily subfolder within your Cumulus installation.
  • These daily backups will be created if Cumulus was left running during the period of interest, or stopped before that period and since restarted.
  • Normally about 10 such back ups are available, each folder has a name based on the timestamp and contains the 6 xxxx.ini files, the current monthly standard data log/monthly extra data log, and the most recent update of daily summary log.

Open as a text file month.ini in the folder whose name is bearing the timestamp after your final rollover, for Cumulus builds 1041 to 1088 the final lowest and highest for each observation in the month will be listed.

In a similar manner if you miss the last day of the year, for Cumulus builds 1041 to 1088 see the final 'this year' figures for last year by opening year.ini from the appropriate backup.

What do the various wind speeds in Cumulus 1 correspond to, with Davis stations?

Davis station firmware supplies two wind speeds, a 3-second average and a 10-minute average (later versions of the firmware also supply a 2-minute average, Cumulus currently doesn't use this).

  • The latest Davis 3-second average is treated by Cumulus as 'Latest' (available via <#wlatest>, matching direction is '<#currentwdir>' and '<#bearing>')
  • The highest of the station's 3-second readings over the previous 10 (configurable by adding AvgSpeedMinutes=N in Cumulus.ini_(Cumulus_1)#Section:_Station where 'N' is number of) minutes becomes the Cumulus 'Gust (available via <#wgust>, no matching direction web tag). Note that the WMO definition of a wind gust is the mean wind speed over a 2 to 3 second sample period (so Cumulus reports this within an extended 10, or as configured, minute period, not the 'latest' gust).
  • The Davis 10-minute average is the Cumulus 'Average' (available via <#wspeed>, matching direction reported as '<#wdir>' and '<#avgbearing>').

Davis VP2 station loggers record a single spot wind speed, so if you restart Cumulus and the software attempts to catch up from the station logger there may be only one or two values to include in the Cumulus average (over 10, or as configured) minutes calculation. Note that if you sample these readings at shorter (real time) intervals it is possible for Cumulus 'Latest' to be lower than Cumulus 'Average' because approximately half of the 3-second wind speeds will be higher and half of them lower than the 10-minute average. If the Cumulus figure seems lower than the Davis figure see #My_Davis_station_shows_a_higher_maximum_wind_speed_than_Cumulus.

What do the various wind speeds in Cumulus 1 correspond to, with Fine Offset stations?

Fine Offset sensors measure wind over 48-second intervals, divided into 24 2-second intervals. At the end of each 48-second period, the outdoor unit (anemometer) transmits two values, the "Gust" is calculated from the number of revolutions of the anemometer in last two seconds and the "Average" from the number of revolutions adding all two second counts in the 48 seconds. The console keeps overwriting the newly received 'Gust' and 'Wind' values to the same area of console memory every 48 seconds, until the station logging interval time is reached, then it moves on to the next memory location, leaving the last values it wrote in the previous console memory location. Note that Fine Offset Consoles can display a 'MAX' figure, this is highest recorded since it was last reset (on touchscreen models multiple touches of the displayed speed will cause maximum speed, or gust, to be shown, and when a max value is displayed continuing to hold touching that value for 3 seconds will reset max to current value). Cumulus maintains its own various extremes for different periods (e.g high wind and high gust for yesterday on its main screen) calculated from all values processed by Cumulus in that period.

  • If Cumulus is not running all the time, on restart it works through the console memory locations and extracts the Fine Offset Wind and Gust in each memory location, i.e. at the station logging interval.
  • While Cumulus is running, it reads the current wind speeds (and direction) every 10 seconds. There are new values only every 48 seconds (i.e. every fourth or fifth read).

Note that the World Meteorological Office definition of a wind gust is the mean wind speed over a 2 to 3 second sample period (not the maximum instantaneous wind speed). So the Fine Offset is reporting gust correctly to WMO definition.

Cumulus, for various reasons, uses different terminology, and also has configuration settings which control how some of the wind values are displayed.

Summary with default selections

  1. '<#wgust>' contains "Calculated Wind Gust (highest value for any 2 seconds in last 10 minutes) Speed" reports highest console gust value in last 10 minutes (this is capturing WMO gust definition over a longer 10 minute reporting interval)
  2. '<#wlatest>' contains "Latest Peak (the value for last 2 seconds in 48 seconds prior to storing) Wind Speed" taken from console gust value (this is capturing the latest WMO Gust)
  3. '<#wspeed>' contains "Current Average (over same 48 seconds) Wind Speed" taken from console wind value

In detail with all the configurations

  • The highest of the Fine Offset 'Gust' values over the previous 10 (number fixed and not configured to match any other interval set) minutes becomes what Cumulus reports as the 'Gust' speed ('<#wgust>'). Cumulus does not report a matching direction for this as a web tag, although it will be somewhere in array '<#wdirdata>'.
  • The value labelled 'Latest'('<#wlatest>', matching direction is '<#currentwdir>' and '<#bearing>') by Cumulus is Fine Offset console 'Gust' value. (Cumulus also adds each new latest value to the array <#wspddata> and moves the index of the array <#nextwindindex> onto the next position in the circular array.
  • The Cumulus 'Average' ('<#wspeed>' matching direction reported as '<#wdir>' and '<#avgbearing>') can be calculated in 3 different ways:
    • The default: If 'Calculate 10-min wind average' is not selected on the Station Settings screen, the console 'Wind' value is reported.
    • If 'Calculate 10-min wind average' is selected, but 'Use speed for avg calculation' is left un-selected; then the average of the Fine Offset 'Gust' values read over the previous N (configurable, defaults to 10) minutes is reported.
    • If 'Calculate 10-min wind average' and 'Use speed for avg calculation' are both selected; the average of the Fine Offset 'Wind' values read over the previous N (configurable, defaults to 10) minutes is reported.

Select value for 'N' using AvgSpeedMinutes=N in Cumulus.ini_(Cumulus_1)#Section:_Station.

How do I set up recording wind speeds in Cumulus 1, with Oregon Scientific and La Crosse stations

La Crosse and some Oregon Scientific weather stations only output a single wind speed. To allow Cumulus to calculate 'gust' and 'wind speed' with different values, select the Station dialogue from the Configuration menu and set Calculate 10 min wind average in the 'Settings' frame, so in cumulus.ini this will produce the parameter 'Wind10MinAverage=1 when cumulus is next stopped.

  • The station's 'Wind' value will then display as Cumulus 'Latest'.
  • A 10 (configurable by adding AvgSpeedMinutes=N in Cumulus.ini_(Cumulus_1)#Section:_Station where 'N' is number of) minutes average of the station's 'Wind' value will then display as Cumulus 'Average'.
  • The highest of the station's 'Wind' value in a 10 minute period will then display as Cumulus 'Gust'. Note that the WMO definition of a wind gust is the mean wind speed over a 2 to 3 second sample period (not the maximum instantaneous wind speed).

See LCMaxWind=X parameter in Cumulus.ini_(Cumulus_1)#La_Crosse_specific: where X is the maximum (uncalibrated) wind speed in m/s that you want to allow.

How do I make Cumulus 1 run automatically when Windows starts?

 Reminder, this FAQ answer is ONLY for Cumulus 1

There is no option in Cumulus to set this up automatically as I prefer to leave it under the control of the user: The safest and most reliable method is simply to put a shortcut in your Startup folder. If you are running Vista or Windows 7, or later versions of Windows, you may find that Cumulus gets blocked by UAC if you try to run it from the Startup folder, in which case it is recommended that you use Task Scheduler instead. See here for a good description of how to do this -

How does Cumulus handle Daylight Saving Time?

Cumulus provides the option for you to use rollover at 9am winter time that is preserved throughout the year so all days are 24 hours long even when clock changes, simply click "Use 10am in summer" on the Station settings.

As far as the timestamps in the extreme logs, monthly log, and the graphs, are concerned; Cumulus doesn't do anything in particular for DST.

  • It generates timestamps based on the clock in the device you run Cumulus on.
    • So basically, at the start of DST (i.e. when the clocks 'go forward' for the summer) you will get an apparent gap of one hour in your data logs and on graphs.
    • Similarly at the end of DST (i.e. when the clocks 'go back' for the winter) you will get an apparent hour of duplicate timestamps in your logs and graphs.
  • You will tend to get better results if you leave Cumulus running during the clock change, because if it is stopped you may lose data,
    • the exact timing of the affected hours depends on the type of station and the times when Cumulus was running/stopped.

... How do Davis stations handle Daylight Saving Time?

Note that there seems to be an issue with Davis stations, either in the console/logger, or in the Davis DLL which Cumulus uses.

  • If you don't have Cumulus running when DST ends (autumn), then when you start Cumulus up again, it doesn't receive all of the logger data it needs to catch up to the present time - the previous hour or so is missing.
  • So with Davis stations, I strongly recommend that you leave Cumulus running at the end of DST, if at all possible.

... How do Fine Offset stations handle Daylight Saving Time?

  • For Fine Offset models without access to a radio controlled clock, if you don't have Cumulus running when DST ends in autumn, then when you start Cumulus up again, the catch up misses off the first hour after the time Cumulus was stopped (unless you have adjusted the time in today.ini by subtracting one hour for end of DST while Cumulus was stopped).
    • This is because the console memory does not time-stamp the data blocks and each memory location simply contains the number of minutes elapsed since the previous memory location was last updated.
    • Cumulus does not remember the console data block used just before shutdown, (after all depending on how long Cumulus has been stopped and the station logging interval, the old memory location could be overwritten by now), and so Cumulus works out a time-stamp based on current clock time and the stored elapsed interval times as it works back through those memory locations.
    • The stored minutes elapsed value will be consistent with the logging interval you selected for the station (might be different to that selected on Cumulus) and that stored value will add an extra minute if a read from the transmitter (every 48 seconds on models without solar sensors) delays a particular log update, However, the console clock (unless radio-controlled) is unaware of DST, it is like a clock without a hour hand, it can only count in minutes.
    • On restart Cumulus just tries to read the appropriate number of hours worth of observations back from the block now marked as latest.
    • For example if it was stopped at 2200 DST and restarted at 0600 standard time, Cumulus catches up with the last 8 hours worth of stored measurements as if going back to 2200 standard time, that means it retrieves back to 2300 DST and has forever lost the period 2200 to 2300 DST.
  • So with Fine Offset stations, I strongly recommend that you leave Cumulus running at the end of DST, if at all possible, to ensure that average temperature, heating/cooling degree days, wind run, and similar calculations are accurate.
  • See Fine Offset forum discussions for further information.

What formula does Cumulus 1 use for values derived from temperature?

see Cumulus_Calculated_Parameters

How does Cumulus know the height of the cloud base?

It doesn't. It uses a calculation which gives the theoretical height above ground level at which Cumulus clouds might form, based on the current temperature and dew point. It assumes that the difference between temperature and dew point decreases by about 4.4 degrees Fahrenheit per 1000 feet increase in altitude. When the two values coincide, the air is saturated (relative humidity = 100%) and Cumulus clouds may form.

How is my rain rate calculated?

For stations which supply a rain rate, Cumulus uses that. For stations which don't supply a rain rate (e.g. Fine Offset and La Crosse), Cumulus simply takes the rain total from the last five minutes and calculates a rate based on that; e.g. a single tip of 0.3mm in 5 minutes is a rate of 3.6mm/hr. When data from the station's logger is used, a similar calculation is performed, but the interval used is the logger interval rather than five minutes.

Where does Cumulus 1 get its this month and this year rainfall totals from?

  • The rainfall totals (for this month, year, and season), are initialised when Cumulus is (re-)started by adding up the corresponding daily totals in dayfile.txt and storing those sums in memory.
    • Don't forget that Cumulus uses binary arithmetic to base 2, that does not correctly represent what in base 10 are decimal places, so you may see slight errors for those using inches and expecting correctness to two decimal places (read up this on internet if you don't understand binary arithmetic).
    • The rainfall totals shown on the This period, This month, and This year screens within the View menu in Cumulus 1 are generated by adding up the daily rainfall totals found in dayfile.txt for the selected period. Using default settings via View menu in Cumulus 1, This month screen for this month excluding today, This year screen for this calendar year (this does always start on 1 January, unless you only started using Cumulus after that) excluding today. Note any rainfall for the current (meteorological) day is excluded as the latest dayfile.txt row is for yesterday. Totals can be shown for any past period, by selecting the required dates, the figures are recalculated when you press the Update display button and will include all days available in dayfile.txt for the chosen period. Important note: The view menu 'This year' screen always calculates the total for a selected calendar year starting in January.
  • Each time Cumulus reads records from the weather station it applies any change to the 'total rain count' against today's total in its memory. This "Count" approach has been chosen because different weather stations output different values, and an independent count is a way of working that can be applied for any weather station.
    • As you will see if you look in diags_folder, Cumulus stores the 'total rain count' figure at rollover, so by maintaining the current figure it can subtract off the start of day figure to deduce the rainfall today and this is shown on the front screen in Cumulus 1, labelled Today. In Cumulus 1 the Edit menu gives access to the Today's rain screen and that provides the ability to edit the start of day figure so that the figure shown for today is correct.
    • If there is no rain in a day, the start of day count will be the same at the start of the next day.
    • Today's rain is added to the figures (as described above) derived from dayfile.txt for what the front screen in Cumulus 1, labels This month, and This year (this last figure is the seasonal total, you can choose for it to start on 1 January or any other month). Thus these figures are updated each time Cumulus receives a rain reading from the station (they all include today-so-far), and these figures will not be displayed if Cumulus is unable to read rain information from your station.
    • The today's total so far at each reading time is also added to the 'recent tag' array allowing total values for the day-so-far at one minute intervals for up to a week ago to be added as web tags to a web template.
  • For the web tags, Cumulus takes its stored sums and adds today's latest total each time, to give the current totals for this month and this rain season (year so far) when processing 'indexT.htm' web template as these figures are shown on that page (not on this month nor on this year templates).
    • Important, for the <#ryear> web tag, and for the 'This year' display on the main Cumulus screen, the processing reads the dayfile.txt for the rainfall season starting with the month set on the station settings screen and stored as the value for attribute RainSeasonStart in Cumulus.ini_(Cumulus_1)#Section:_Station (its default is January).
    • If you have set a 'year to date' value and Cumulus is being re-started when the year specified beside that figure matches the current calendar year, your year-to-date amount is also added into this year's total. This should normally only be relevant in your first rain season of operating Cumulus, but could be used if in any season you needed to add an extra amount because for some reason you had a gap in your recording period. Do be aware that if you select a rain season starting in a month other than January, the year to date figure will stop being added on 1 January because the year specified next to the figure to add on will then be the previous calendar year!
    • There is no corresponding setting for amending the total for the first 'this month' of Cumulus operation. The only way round this is to manually change the rainfall in dayfile.txt for the first day of operation to include rainfall on all previous days of month, but that could potentially cause you to set the maximum daily rainfall extreme record wrongly.
  • Note that you need to stop and then restart Cumulus to update these initial values that are stored in memory and get any corrections you made to rogue values in the daily summary log (or year-to-date) reflected on the main Cumulus screen and in web tags.

The built-in dayfile.txt editor is used if it is necessary to amend the daily totals (to correct any monthly, rain season, or calendar year, totals); the built-in all-time (or monthly records) editor(s) is used if it is necessary to regenerate the extreme records from dayfile.txt; see FAQ about correcting incorrect rainfall displays.

How do I reset all my data to start again from scratch?

Stop Cumulus 1 and delete all of the files in the data folder. You may also want to edit the 'StartDate=' line in cumulus.ini to set the date for the start of your data, if you are starting again on a different date, although Cumulus 1 does not make any decisions based on that date, it simply outputs it twice (!) on one standard web page.

How do I localise Cumulus 1 to my own language?

Cumulus does not directly support languages other than English. It was never intended for use in other languages, and it is not possible to add support for this now. However, the text used for:

  • Forecasting
  • Moon phases
  • Beaufort Scale
  • Trend descriptions
  • Compass points
  • Graph titles
  • Extra sensor channels

can all be customised by using the strings.ini file.

This wiki page Other Languages has some obsolete (valid in 2009-2010) information about customising what were the standard web pages in versions of Cumulus 1 up to 1.8.x. The translations there are NOT compatible with later Cumulus 1 versions.

On the downloads page you can find third-party alternative web pages, these typically include some language translation modules, but beware that these may not be maintained to work with latest versions of Cumulus.

Can I connect/disconnect my weather station while Cumulus 1 is running?

No. You must make sure your weather station is connected to your PC and switched on, before running Cumulus 1. Do not disconnect your station while Cumulus 1 is running.

How does Cumulus deal with extra sensors?

By default, Cumulus 1 deals with weather stations incorporating solar sensors, if you have selected the relevant station 'Type' or 'Display solar/extra data' in configuration, but it has some capability to deal with extra sensors added including the Blake-Larsen Sun Recorder.

Cumulus 1 has the ability to input, log, and display Current Values/Outputs from the Hydreon Optical Rain Sensor - Model RG-11 and from either Oregon Scientific or Davis extra sensors. Only today's and yesterday's total rainfall from a Hydreon sensor are available in today.ini and yesterday.ini respectively.

For some Oregon Scientific models, the temperature from an extra sensor can replace the temperature from the main sensor for processing by Cumulus 1, but all extra sensor values are stored in a series of monthly log files for extra sensors.

No other processing is performed for Davis extra sensors, but past values are retained in a series of extra sensor monthly log files. The file strings.ini is used to customise the description associated with extra sensors.

What is this "Solar Max" value which Cumulus is displaying?

 Reminder, this FAQ answer is ONLY for Cumulus 1

It's the current theoretical maximum solar radiation value at the current date and time at your location. It is calculated using the Ryan-Stolzenbach formula, and uses the 'transmission factor' configurable in the station settings to allow for the effect of transmission through the atmosphere. The figure is not particularly useful in itself; it is used if you have a solar sensor, to compare with the current solar radiation reading, in an attempt to determine whether the sun is currently shining or not.

My Fine Offset console says the memory is nearly full - how do I clear it?

You don't need to, and it's much safer if you don't; clearing the memory could lead to a loss of data. The memory indicator on the console has no effect on the logging of data; the console will automatically start re-using the oldest memory locations. As long as you are running Cumulus (at least occasionally), Cumulus will have downloaded the data it needs from the console, so the console is free to overwrite the oldest data when it needs to.

How do I get my Davis station with USB working with Cumulus 1?

 Reminder, this FAQ answer is ONLY for Cumulus 1

Cumulus cannot drive the station in USB mode, you must install 'virtual serial port' drivers, and configure Cumulus to use the virtual serial port. Make sure you have the station connected to the PC during the following operations.

You should first make sure that you can use the station with Weatherlink, in serial mode. If you have not already installed the Weatherlink software, install the version which came with your weather station. You should then upgrade to the latest version of Weatherlink; you can download the update from the Davis web site, here.

You now need to install the 'CP210X USB to Serial Converter'. You may find a link on your Start menu under 'Weatherlink'. Alternatively, you should find it in the folder where Weatherlink was installed, under 'Support' then 'Utilities'. Davis also make version 2 of this utility available on their web site, here, and you may find that this version will work for you if the installed version does not. It should be clear from the messages output by the utility that it has successfully switched the logger to serial mode.

It's a good idea to then update the driver to the latest version from the Silicon Labs web site, particularly if you use Windows 7 or later. You can download it here - click on 'VCP driver kit' under 'Download for Windows XP/Server 2003/Vista/7...' to begin the download. Run the executable once it's downloaded.

At this point, it's best to restart your computer.

You should now run Weatherlink, and attempt to connect to the weather station in serial mode. Weatherlink should find the appropriate COM port number automatically. If not, you can find it under 'Ports (COM & LPT)' in the Windows device manager. Look for the port called 'USB Serial Port (COMn)', where 'n' is a number. That's the number of the port you need to use in Weatherlink. If you cannot get Weatherlink to work using this virtual COM port, it is unlikely that you will be able to get Cumulus to work either, so either contact Davis support, explaining that you are trying to use the virtual serial port drivers because you want to run third-party software, or ask in the Cumulus forum, someone may be able to advise.

Once you have Weatherlink connected and working via the virtual serial port, close it down, and start Cumulus.

In the station settings in Cumulus, select the appropriate station type for your station; under 'VP Type' select Serial; in the serial port section enter the COM port number that you found earlier. You may need to restart Cumulus at this point. It will then start displaying live data. Note that the it deliberately does not download any historical logger data from before the current point in time. When you run it subsequently, it will download logger data to catch up if necessary from when you last ran it, but never from earlier than when you first ran it.

If you still having difficulty, the Davis Weatherlink manual offers this advice, which may be useful:

"Included with the WeatherLink software is a utility that allows you to convert a USB data logger from a direct USB data logger back to a USB data logger that emulates the serial port. To use this utility, select Convert USB to Virtual Serial in your WeatherLink program group on the Start menu of your computer (Start>AllPrograms>WeatherLink>Convert USB to Virtual Serial) and run the utility to convert your data logger. Please contact Davis Technical Support (“Contacting Davis Technical Support” on page 26) for more information."

Why does Cumulus 1 do some things the way it does, when there are better ways?

 Reminder, this FAQ answer is ONLY for Cumulus 1

This text is by the author, Steve Loft

Cumulus was originally something I 'knocked together' quickly when I got my first weather station, simply because I couldn't find any other software anywhere which I was prepared to use.

No 'design' went into it, it was really just a prototype. Some of the things I did were just quick 'hacks' that I intended to fix when I did it 'properly'. But I never got around to going back and doing it 'properly', and it was never my intention that anyone else would use it. But I was persuaded to make it available for others, and then to add more and more enhancements.

The fact that it works with several different types of weather station means that much of it is a compromise; it doesn't use certain features of the weather station which it could use if it were dedicated to that type of weather station. For example, it typically does not use any high/low data that the station might store internally. Instead, it maintains its own high/low data from individual readings. There are a number of reasons for this; the fact that Cumulus supports an 0900-0900 day, and the weather station does not, and the fact that typically Cumulus maintains far more high/low values than the station does, and these need to be self-consistent.

So yes, I am aware that some of things that Cumulus does may seem strange, but it is simply not possible for me to start again from scratch, this is done in my spare time.

And it is not possible for me to effectively produce separate versions of Cumulus specifically for each type of weather station. If you don't like the way Cumulus does certain things, do what I did and write your own software!

Can I run 2 copies of Cumulus 1?

3 options:

  • You can install Cumulus 1 on more than one machine, but each copy must connect directly to its own weather station (one station connected per Cumulus installation).
  • You can install 2 copies of Cumulus 1 in different paths on a single PC, if you have two weather stations and Cumulus is able to distinguish between them, e.g. they are from different manufacturers, or both are serial port stations (different ports), or one is USB and one is serial, or one is a Weatherlink IP. In other words the combination that does not work on a single PC is two USB stations (including clones from different suppliers) from the same manufacturer. Note that Davis stations with USB loggers are serial port stations as far as Cumulus is concerned, so there are no problems using multiple copies of Cumulus with multiple Davis stations on the same PC.
  • It is possible to back up the Cumulus files from one installation running off a weather station, and briefly have another reduced functionality copy just looking at historic data without ever any updating (the second Cumulus is set up as if reading from an EasyWeather.dat file, but not given a path/file name) - see Easyweather.dat section here.

Don't attempt to run Cumulus 1 and MX at same time, they cannot share a single weather station. However you can with a single weather station, stop Cumulus 1 and then run MX if they use different data folders, then later stop MX and run Cumulus 1.


 Please note, these answers are written for Cumulus 1.x.y.

The equivalent page for Cumulus MX is Cumulus MX FAQ.

My 'Error' light is flashing

 Click on it, and a window will open describing the error. It may just be a temporary ftp problem. If you want to stop ftp errors being reported in this way, you can turn them off in the display settings ("Show FTP errors on error log window").

My ‘new record’ light has stopped flashing

 It is the normal situation that the light does not flash. The ‘new record’ light only flashes when an all-time record has been broken. It stops flashing if you click on it or restart Cumulus, until another all-time record is broken. When you first start using Cumulus, inevitably the light will flash a lot, even if you cancel it, as you will be breaking records constantly. After a while, it will 'settle down' and not flash so often.

I installed a new version and my web page templates got over-written

 The supplied web page templates are part of Cumulus and will be over-written on upgrade.

  • If you want to create your own web pages, don’t edit the supplied ones, place your templates in a different folder and use the ‘extra files’ facility.
  • From version 1.8.9, the installer offers the option of not over-writing the web templates; it unconditionally also installs them to a sub-folder of the web folder called 'originals', so you can refer to the originals if required, even if you chose the new option not to over-write whatever template files are already being processed in the web folder.

I can’t find my data files!

 You’re probably running Windows Vista/Windows 7/Windows 8 (or one of the corresponding server versions of Windows). Look in C:\Users\[username]\AppData\Local\VirtualStore\Program Files\Cumulus - note that this is a 'hidden' folder. Ideally, to avoid this situation, you would install to somewhere outside the Program Files hierarchy, as recommended in the readme.txt.

I can't save my NOAA reports!

 You've probably corrupted your Cumulus.ini_(Cumulus_1) file in the default Cumulus folder. See Cumulus.ini_(Cumulus_1)#Section:_NOAA. It can only be edited either (if Cumulus is stopped) with an external text file editor or (with Cumulus running) using the NOAA Setup in the configuation menu. Pay attention to where the quotes are required for the file names, and check that you have an allowed date format (see Webtags#The_format_used_for_naming).

My sunrise and sunset times are wrong

You've almost certainly entered your co-ordinates incorrectly, or not entered them at all - on the station settings screen.

  • You must enter DEGREES, MINUTES, and SECONDS, no other format will work.
  • Make sure to use unsigned whole numbers for degrees, minutes, and seconds, with a 'W' for your longitude if you're West of the Greenwich meridian (e.g. if you are in the United States), and the appropriate letter for your latitude (N for northern hemisphere, S for southern hemisphere).

If you are not familiar with the degrees/minutes/seconds standard format and have your co-ordinates in some other format, there are pages on the web which will convert for you. One such is here:

One other less likely possibility is that you have set the wrong time zone on your PC.

The Moon rise or set time is showing dashes.

The moon doesn’t rise and set every day, the dashes appear when that event doesn’t occur on that particular day. The period between a moon rise and set is approximately 12 hours and 25 minutes, on average. The moon rises (or sets) approximately 50 minutes later, on average, each day. It therefore follows that sometimes the moon will not rise or set on a particular day - i.e. it had risen the previous day, or will set on the following day.

The Moon image is just black

It's probably a New Moon.

End of Day Rollover Failures

 The yesterday values on the Main Screen under "Recent Extremes" are not shown correctly:

  • EITHER when the end of day rollover has not taken place.
    • The usual cause of this is allowing your PC to 'sleep' while Cumulus is running.
    • The support forum mentions a few other causes.
    • Cure this (if you have a weather station type that has an internal log that Cumulus reads) by looking in "Cumulus\backup" folder, and finding a backup directly in that folder or in "daily" sub-folder for just before the problem. With Cumulus stopped, copy all the files in that backup into the "Cumulus\data" folder, and then restart Cumulus.
  • OR if Cumulus was unable to read observations from your station during that day, but can today.
    • You can try the same cure, but may not be able to recover the lost information in this case.

If you are viewing or editing log files at the time when rollover takes place, it is likely that some parts of the daily rollover will fail.

  • Cumulus 1 provides the functionality to view any log file and you can update the log files that contain extreme records or the daily summary.
  • Do make sure you have exited out of the built-in viewer or editor before rollover is due.
  • When using an external editor, close Cumulus before opening any Cumulus file.

Why do I have some unexpected zero figures?

Cumulus may not be able to update some values/extremes, leaving them at zero, if:

  • EITHER you are allowing your PC (or its peripherals) to go into sleep/standby while Cumulus is running,
  • OR you have more than one copy of Cumulus attempting to interrogate the same weather station,
  • OR you are opening/closing Cumulus down very close (within the time for two logger data cycles) to before/after roll-over (this is a restriction due to the way the processing of logger data works).

Other FAQ and the forum describe further each of these cases.

I’ve ‘zoomed’ a graph, how do I get it back to full size?

 Drag from lower right to upper left.

Cumulus can't read a data update from my station

CUMULUS RUNNING If Cumulus error light comes on and message says "Data input appears to have stopped":

  1. Could be interference:
    1. Another software package is attempting to interrogate the station at (almost) the same time, so inhibiting a further connection
    2. A process on your computer (possibly one that you initiate using Cumulus 1) terminates with an error, making Cumulus miss one of its normal station reading actions
    3. Other devices could be affecting, either the frequency of any radio transfer by your station, or the signal passing along your USB connection lead
  2. Could be a connection lead has been knocked and so your USB connection has ceased
  3. Could be USB port has setting that allows it to sleep
  4. Could be you are making some change on your station console that prevents Cumulus reading it at the same time
  5. If you have one of the Fine Offset clones, make sure you have configured your relative pressure correctly. If Cumulus finds an 'impossible' value, it will ignore all data from your station.

CUMULUS RE-STARTED If Cumulus does not read catch-up data from the station logger:

  1. Might be problem with connection lead, or interference from nearby electrical unit.
  2. Your station type may not have a logger, if so Cumulus cannot read anything from station while software was not running.
  3. There is a bug in the Davis DLL (Dynamic-Link Library) that Cumulus 1.x.x uses, where it never downloads the last archive record; so if there is only one to download (compare how long Cumulus was stopped with logging interval on your Davis station), it doesn't get any at all. (See here for opposite problem). Cure this by ensuring if you stop Cumulus you either leave it stopped for less than Davis logging interval time, or don't restart until after at least 2 logging intervals.
  4. You have not selected "Use data logger" in the Settings section of the Station settings screen accessed from Configuration menu. Correct this:
    1. Stop Cumulus after changing this setting
    2. Look in Cumulus\backup folder (or its daily sub-folder) for a folder of .ini files prior to the problem, copy all those files to overwrite the ones in Cumulus\data folder
    3. Re-start Cumulus, it should use revised start date/time, and read the station logger for the whole re-wind period
  5. If there is another problem, read the instructions accessed from "Please read this post before posting" at the top of the support forum page including the request to zip up the contents of the Cumulus\diags folder when asking for such support.

On restarting Cumulus, it did not successfully read all data from when it last ran

Assuming you use the type of weather station that does have an internal memory that retains observations that have already been read by your computer (and assuming that you have not left Cumulus off for so long that some of the days you want are no longer there)...

  1. Use the 'rewind feature' of Cumulus. Look in the backup folder for the backup which Cumulus took when it first started up today. Stop Cumulus, copy all of the files from that backup folder into the data folder (overwriting the files which are there) - this restores Cumulus to the state it was in before you ran it today. Make sure nothing else on the computer is running that might affect either your station or Cumulus log files. You can look in today.ini to see the date and time that you will rewind back to. Start Cumulus and it should then download the data (from the date and time in the "today.ini"), to get up to date. (Ignore remaining paragraphs if this has worked).
  2. As mentioned elsewhere if option 1 does not work, you can choose an older back-up and rewind back further providing the information is in the station logger. Remember however, that when you restart Cumulus it will only have access to observations at the station's logging interval, so any extremes between logging times previously picked up by the frequent querying of the station while Cumulus was previously running during the period you are now rewinding may be lost.
  3. If Cumulus still cannot catch-up, then you can try this more risky solution, you can edit timestamp in today.ini to exactly match a logging time in your station, the restart should then read all subsequent timed storage locations in the station. This only applies to makes of stations that store the exact time with each logging, not to station types that only record duration since previous logging.
  4. If you are very skilled in understanding how Cumulus uses its various Log Files, it is possible (when you stop Cumulus) to back up all the Cumulus log files, before you perform the rewind and a restart, then stop Cumulus again and partially merge data from old and new files, this might enable you to keep some extremes that would otherwise be lost by the rewind, finally do a normal restart.

Cumulus read some invalid figures from my station

If you have:

  • just started using Cumulus,
  • just re-started Cumulus and you are only getting bad data when you start Cumulus up (i.e. when it is using archive data from the station logger),
  • or you have just changed some settings,

... check you have the correct station type selected (see the Cumulus Help for the settings screen).

 Choosing the wrong station type means individual items of information are not correctly assigned to weather parameters. Cumulus knows what is at what location for each station type.

  • Is the information correct on the station console (i.e. not a fault with a sensor), but incorrectly displayed on Cumulus screen (i.e. transfer problem)?

Check all your settings on Cumulus, or see a previous question.

  • If the station itself shows incorrect figures, a sensor may have a problem (mechanical or electrical failure, obstruction by animal activity) or a battery may need replacing.

Over successive versions of Cumulus more and more code has been incorporated to deal with the way some stations are prone to reporting rogue readings.

  • Ensure you are using the latest Cumulus build, if you are using an old version you will not have any enhancements made since the earlier build that might improve the way Cumulus reads from your station type.

In general, if Cumulus 1.x.x identifies an odd value for up to 6 times, it will reuse the last good value instead. Depending on how frequently Cumulus is able to read from your station, that can represent up to 5 minutes. That is designed to be long enough for you to spot the problem and deal with it. Sometimes the problem will right itself within that time. After that time, a problem with reading temperature, humidity, wind, or pressure, means Cumulus cannot calculate derived values, the last successful read is considered too stale to reuse, and by default Cumulus will stop any further processing.

Fine Offset stations are prone to reporting the odd nonsensical value, and Cumulus has the ability to compare successive readings:

  •  From the Configuration menu select Calibration and in the Spike removal frame you can specify "the maximum differences between successive values" that Cumulus is to tolerate.
  •  See the Help for that screen, and note that spike removal applies while Cumulus is running, it is not applied to catch-up readings from the station's logger.

Possible Cure: The purpose of the backup files is to allow Cumulus to be 'rewound' to a particular point in time. It simulates the situation where someone had closed Cumulus down at that point, and is only now starting it up again, and needs data to be downloaded from the station's logger to catch up to the present time. Obviously this cure will not work if your station type does not have a logger (one is needed for Cumulus to read old readings again).

  • If you have only installed Cumulus a few days ago, or have just re-started Cumulus after it was stopped and encounter multiple rogue readings in the catch-up from the station logger; one possibility is to stop Cumulus and find the backup files that it took when you started it up (or just after the previous roll-over time), copy those files into the data folder, overwriting the ones that are there, then when you start it up again it will rewind back to the time in that back-up, and could sort itself out.

 The Cumulus 1 Diagnostic log often contains useful information for sorting out what has been read, which values have been ignored, and which highs or lows may have been updated incorrectly. Note that automatic backups are made just after roll-over time because restarting Cumulus when there are no logger records to read before roll-over has been known to cause problems. Therefore, the backup to choose might be one with the date before when the problem occurred, but remember that any calculations Cumulus makes are based on readings at least every minute when Cumulus is running, but for the catch up period such calculations can only use the readings available at your station's logging interval. Note if you choose a later backup and it does not work, you can always then repeat the 'rewind' with a earlier backup.

How to restore a corrupted log file

Full information about all the log files is elsewhere Category:Log_Files, so you can study the notes linked from there, but here is a very quick summary.

You may want to read Calculate_Missing_Values for more information.

Cumulus will create a copy of each of the logs (.ini and .txt) in the backup folder, both at end of day rollover, and when the software is (re-)started.

If the corrupted file in 'data' folder is a log file holding extremes (not the detailed log created for each month nor 'today.ini'), then the easiest way to remove false extremes recorded recently is to to overwrite the current file with the one from the most recent back-up.

Since 'today.ini' is updated very frequently (every time Cumulus interrogates your weather station), it is not advised that you overwrite that file, unless you are able to do a rewind as described in earlier answer.

If you were to use the backup folder copy of the detailed log, you would lose all of the stored values since the backup, so again only do that in a rewind context where all the files from the backup are overwriting those in data folder, and you simply want to copy in what is still in any station logging memory.

Cumulus 1 provides editors - go to Edit menu and pick the relevant extremes file, the either type over the figures that you want to change or use the buttons that load the more detailed log files and then figures from them can be copied into extreme file. There is an option (in the view menu) to read the latest detailed log for the current (or past) month, but there is no built in editor for those files.

You may want to read Correcting_Extremes for more information, but here is a summary.

  • Remember 'alltimelog.txt' logs each change made to 'alltime.ini' so you don't need to correct the former, but it can help you know how to regress the latter.
  • "speciallog.txt" (if used) holds internal temperature and internal humidity, it does not get copied to backup folder, so you need to back it up yourself.
  • 'yesterday.ini' will get overwritten at end of day, so it is rare to edit that.
  • "dayfile.txt" has a new line appended to it at the end of each day, if you go back to the backup copy and you lose the latest line, then most of the information can be extracted from the 'today.ini' in the same backup folder, but you need to understand the process and content differences as explained in the Wiki for the two files.
  • 'year.ini' and 'month.ini' record extremes shown for this year and this month, the diagnostics logs created in the sub-folder diags record each new extreme added to these files, so you can work through the diagnostic logs to identify what to correct.
  • "monthlyalltime.ini" is essentially a more complicated 'month.ini', it separates out extremes for each month of year. Any change in the diagnostic logs for the current month may, or may not, affect "monthlyalltime.ini", but again searching through the logs should help.
  • 'log.xml' is another file that Cumulus does not copy to the backup folder, so you should back it up periodically. It is only found in Cumulus 1 and is edited using the 'Weather Diary' screen in the 'View' menu. Although it can be edited by a 'XML' editor, I advise against it, as the way that the field 'RowState' is calculated is complex, and if you corrupt the file, Cumulus 1 will crash.
  • "mmmyy.txt" (naming varies depending on computer settings) is the detailed log mentioned above

I get very large amounts of rainfall shown, or other high readings

Fine Offset stations have a habit of producing unbelievable readings, and Cumulus filters many of these out automatically. You can also use the 'spike removal' settings on the calibration page, and Cumulus will then filter out large changes in readings. Please read the help for how to use these settings. Another possible explanation is that you have chosen the wrong station type in the Cumulus station settings. You should only select the "Fine Offset with UV/Light sensor" type if your station actually has SENSORS for these. Your station may have solar CHARGING, but this is not the same as having a solar SENSOR, and so you should choose the "Fine Offset (WH1080 etc)" type. Typically, stations which do have solar SENSORS have a model number which starts with a '3', e.g. WS3080, and stations without solar sensors start with a '1' or '2'. Selecting the wrong type of station will cause Cumulus to misinterpret the logger data read from the station (which it uses when it starts up) and hence incorrect readings will result, typically when you restart Cumulus.

If you have bought your Fine Offset station in recent years, a USB lock-up problem is very common and around 50 threads in the support forum are about this. Correcting the lock-up often requires resetting the console, and that can have an undesirable side effect of Cumulus then getting invalid data from the station. The correction of invalid rainfall figures is covered in subsequent paragraphs. Errors in other measurements are one-off errors and should not affect subsequent readings. You still may need, as explained in the relevent Wiki entries, to delete a single line from your monthly log file with rogue values, and correct any incorrect extremes that have been recorded in the various record log files.

My station invented some rain that didn't really occur, and I want to set it to zero (or some other figure)

Cumulus does include some code to try to ignore some obvious rain errors:

  • For example, if the station reports negative (the counter that Cumulus uses decreases in value) rain, Cumulus will normally ignore that, but if for 6 consecutive readings the rain cumulative count stays below what it was before, Cumulus will normally accept the new count as a new starting point.
  • While Cumulus is running (not when catching up with stored past values from the station log), it will ignore large increases in rainfall. (See below).

Because many positive values are realistic, Cumulus generally will accept those odd increases as a result of accidental knocking of a tipping bucket gauge, due to wind effects on the gauge, or even due to the station electronics generating a rogue reading. The sub-answers below explain how to correct such errors.

(Invented rain) Error in today's total

Easy - correct today's total using the 'today's rain' editor on the edit menu

(Invented rain) Error in date/time of 'Last Tip'

You must exit out of Cumulus and then edit today.ini to change the LastTip=(usually helpful to look up previous last tip date/time in a recently backed up today.ini) parameter.

(Invented rain) Error in number of consecutive days with or without rain

  1. The counts are for completed days, not part days. The threshold for whether a day counts as a wet day is set in the optional parameter RainDayThreshold= -1, and the parameter NoFlashWetDryDayRecords=1 is also relevant.
  2. Remember that 'ConsecutiveDryDays' and 'ConsecutiveWetDays' do not include today, they reflect the daily rainfall amounts stored in the daily summary log.

To edit the count reported by Cumulus, stop Cumulus and edit the today.ini log file by changing the integer value. Remember, that invented rain can affect monthly, annual, all-time, and monthly_all_time extreme records, and you may need to edit these as described in sub-answers below.

(Invented rain) Error in yesterday's total

  1. edit the total for the relevant day in dayfile.txt, (using the dayfile.txt editor available in Cumulus 1 on the edit menu, use any external text editor for MX).
  2. optionally edit yesterday's total (which is only held temporarily for display purposes) in today.ini, while Cumulus is stopped.

(Invented rain) Error in total or high rainfall rate for any day before today

Just edit the total or rate for the relevant day in dayfile.txt, using the the daily summary log file - dayfile.txt editor on the Cumulus 1 edit menu. Don't edit the daily summary file close to roll-over time.

(Invented rain) Error in total, or extremes, for this month and/or this year

See next FAQ. Once you have corrected the daily totals (or high rainfall rates) in dayfile.txt, you can use the editors (on the Cumulus 1 edit menu) for 'This Month' and 'This Year' to fetch the corrected values from dayfile.txt (or enter figures manually).

(Invented rain) Error in all-time extremes or month-by-month all time extremes

Cumulus stores the following rain extremes; for all time and for every January, February ... December:

  • Highest rain rate
  • Highest hourly total
  • Highest daily total
  • Highest monthly total
  • Longest dry period
  • Longest wet period

The correction procedure for all these is as briefly described in this FAQ and more fully described in Correcting_Extremes.

To see the previous value for all-time records see Alltimelog.txt. If your all-time records, or month-by-month all-time records have been affected, in Cumulus 1 you can use the built-in editors. The Cumulus 1 editors can fetch the correct values after you have corrected dayfile.txt.

(Invented rain and) Rain Counter

Cumulus uses a counter supplied by the station to determine its rainfall data (exactly what that counter is, depends on the type of station). A search of the forum will help for your particular model, for example for some models there might be a counter that represents rain since station bought (or since it was reset), for some stations Cumulus will use an annual total supplied by the station (that resets each new year).

If the rain counter is reset by the station for some unexpected reason, you will have to accept that, and let Cumulus handle it - it does its best to cope when the rain counter changes unexpectedly. Assuming it doesn't change unexpectedly again, you should find that the rain figure is only affected for one day, and then you can amend if necessary subsequently as per other sub-answers here. You can see the counter value being used by Cumulus labelled "raindaystart=" in the diagnostics file (for cumulus 1 - "Cumulus\Diags\cumulus.009") and labelled "start=" in "Cumulus\data\today.ini".

(Invented rain and) Other rain figures

Note that other rain figures, such as 'rain last hour', 'rain last 24 hours' and 'rain since midnight' depend on a sensible progression of the rain counter described in previous sub-answer, so it's not easy to correct this; it is easier to wait until the erroneous figure is far enough in the past so as not to affect the calculation of these 3 other values. Note that if you're using a midnight start of day then you don't need the 'rain since midnight' figure anyway, as it is normally the same as 'rain today', and that figure is much more easily corrected.

If you really do want to try to correct these other rain figures; you would need to stop Cumulus, then find (for the period in question), the correct standard log file field 11 (assuming date is field 0), which stores the Cumulus 'rain counter' values, and edit (increasing the value in the count field, decreases the difference to the next (or current) count, and therefore reduces the rain in the in-between period) so they are correct relative to the current value of the rain counter (i.e. the latest one logged).

(Invented rain) Error prevention by Spike removal

  1. It is better to try to avoid spurious rain being recorded in the first place.
  2. Cumulus attempts to ignore large increases in the rain total automatically, and is quite often successful.
  3. For 'hourly rain' and 'rain rate', you can set 'spike removal' settings on the calibration settings screen. The value you set here, is the maximum change allowed between successive observations. Rain Rate corrections apply only to Fine Offset and La Crosse stations (which are known to occasionally produce faulty rain readings).

(Invented rain) More information

There is more information about correcting rogue data elsewhere in the Wiki, see Correcting_Extremes.

My monthly and/or annual rainfall totals are wrong

Cumulus calculates these when it is restarted, holds the values within memory, and increments them as required while it is running. This FAQ in the previous section #Where_does_Cumulus_get_its_this_month_and_this_year_rainfall_totals_from.3F has a concise description of how Cumulus calculates these figures.

  • The rainfall total shown on the This month screen within the View menu, is calculated from summing dayfile.txt totals for a selected month, and so for the default current month will exclude the current meteorological day.
    • The rainfall total for today so far is added for the web tag <#rmonth>. If too small a figure is shown, then the most likely issue is that your dayfile.txt is corrupted and Cumulus cannot read one or more lines. Such corruption might be introduced if you have had a power blip while Cumulus was writing to the file, or if you have viewed the file in a Microsoft tool that might have introduced unwanted characters.
    • The Cumulus editor for amending dayfile.txt arranges the fields in columns and you should be able to spot when the fields in one line don't match others. The editors for monthly records (and others) have a facility to read dayfile.txt that can pick up some errors in this file and tell you the line number of the first error.
  • The rainfall total shown on the This year screen within the View menu, is calculated from summing totals in dayfile.txt for a selected calendar year. For the default current year, it will exclude the current meteorological day.
    • Note that for Cumulus 1 the value labelled "This year" in the rainfall frame may not be the total for this calendar year, as you can choose it to start in any month (see next point).
  • The rainfall total reported by the <#ryear> web tag is for the rainfall season to date, it is calculated from taking today's rain and then adding the sum of the totals in dayfile.txt starting with the first (meteorological) day of the month specified in the 'rainfall season' frame on the station settings screen within the Configuration menu, until the end of dayfile.txt is reached. So check you have specified the right starting month there before deciding the rainfall total shown is wrong. This is the same figure as is shown on the main screen of Cumulus 1 for "This year" in the rainfall frame.
    • If you need to, you can specify a year-to-date total to add in for the period up to the point where you started using Cumulus, so that your first year’s total is correct. This is also on the Station Configuration screen. Make sure you specify the first Cumulus operating year here, otherwise the extra will be added to the annual total for the wrong year! Do note, if your rain season starts in a month other than January, the extra is added throughout the calendar year specified, it is lost when the season swaps to a different calendar year, and if you change the specified year then it will also apply to the next season!

See immediately preceding FAQ correcting rainfall for how to correct errors in total for particular days and how to correct the high extremes for the various periods.

In all cases, wait until Cumulus has written the next log entry (i.e. wait the number of minutes that you have set as the Cumulus logging interval), then restart Cumulus to get the monthly and annual totals recalculated from correct daily totals.

If you need to correct within day values for trend graphs as well as the longer period totals, provided you know roughly when the rogue rainfall was recorded, find (and edit) it in the Standard_log_files, field 11 (assuming date is field 0) is the count used to derive other parameters. Increasing the value in the count field, decreases the difference to the next (or current) count, and therefore reduces the rain in the in-between period.

The ‘gust’ line has disappeared from my graph

 You probably have Cumulus set to calculate a 10-minute average, and your logger period is 10 minutes or longer, so your gust comes out the same as the average when using data from the logger. Depending on your weather station type, there are a few things you could try, to improve things. Decrease your station's logger interval, and if you have Cumulus calculating the wind speed average and you have a Fine Offset station, set 'Use speed for avg calculation'.

My ‘gust’ values are the same as my ‘average’ wind speed values.

As above, you probably have Cumulus set to calculate a 10-minute average, and your station logger period is 10 minutes or longer, so your gust comes out the same as the average when using data from the logger. See the previous FAQ for suggestions on how to improve this.

I’ve just installed Cumulus, and it didn’t download all the old data from my weather station

Cumulus deliberately doesn’t attempt to download any data from before the point when you first run it.

  If you wish, although this isn't recommended:

  1. Ensure you have run Cumulus at least once, then stop Cumulus
  2. Edit today.ini (in the data folder), look for the ‘Timestamp’ line, then carefully sticking to exactly the same format as is currently in the file, change the date and time to your earliest available data in your weather station logger (or just before if you don't know exact time)
  3. Optionally, if you have only just started using Cumulus, so you have nothing useful to lose, you could delete all of the other files in the data folder, and delete all lines in the "today.ini" other than those shown in the extract below (with dates modified appropriately).
  4. Now restart Cumulus
    • if you did step 3, processing will start again with just the data from the station's logger.
    • if you have existing files in data folder when you restart, you will probably need to edit your log files in the data folder as you may have duplicate entries and/or entries out of order. Your rain totals will almost certainly also be wrong - the total for "today" in particular. See the FAQ entry about correcting rainfall data.
  5. Note that if you do this, it is at your own risk, and you will need to sort out any issues which may arise yourself.

Timestamp=10/04/2012 10:00:00

Note that this method does not work for the Oregon WMR200 station types because this station deletes logger entries when they are downloaded, and there is no mechanism for retrieving logger entries for a particular period - it just sends all the entries that it has. You may be able to circumvent this by missing out step 1 above, and before you run Cumulus 1 for the first time, creating a today.ini file in the data folder, with just the items shown above in the file. Change the dates and time to match the point from which you want Cumulus to start downloading data. If the station has already sent the data, this may not work, unfortunately.

If you stored data from your weather station (on another file-based system) before you first ran Cumulus, then you may be able to (using a text editor outside Cumulus) generate standard logging files for the pre-Cumulus period. See elsewhere in this Wiki for more information on what you can then do with those files within Cumulus.

I have inserted pre-Cumulus data and now I get errors

Probably some of your inserts used the wrong format (blank rows, fields with real numbers where integers expected, alternatively missing or duplicated fields). See Category:Files with Comma Separated Values. Note that Cumulus 1 will only flag errors in the log files that it reads (e.g. those relating to the period for which it displays trends graphs). Check all the log files you have amended.

I have inserted pre-Cumulus data making 'Records began on' this_date wrong

You do NOT need to change anything in station section of cumulus.ini for Cumulus 1 to recognise earlier data in log files in its data subfolder

There might be confusion about the terminology Records, in the Cumulus usage it does not mean when was your earliest data, it means when did Cumulus start tracking extremes (see Correcting_Extremes#Introduction (it does not say Data recording began on). You should update the extreme records for the inserted data, as advised in Correcting_Extremes before you make the changes suggested below.

'Records began on' this_date appears in TWO places in the example template file called recordT.htm:

  1. after the h2 heading is <p>Records began on <#recordsbegandate>. Here are the extremes recorded since then.</p>;
  2. at the start of the table is the <caption>Records Since <#recordsbegandate></caption>;

There are alternative ways to correct this (do any one or any combination):

  • You can manually replace the <#recordsbegandate>, with any date as ordinary text, in either or both of those places.
  • You can manually replace either Records began on or Records Since with Cumulus began on leaving the web tag unchanged.
    • You can change the other one, not changed above, to read Imported data starts and replace the web tag with the new date.
  • You can stop Cumulus, and manually edit station section of cumulus.ini within the main Cumulus folder.
    • Change the "StartDate=" line so the value for that property has the date you want. Be sure to use the same format for the date.

Like most FAQ on this page, this was written for Cumulus 1, please be aware that MX works differently, and so this does not apply!

Cumulus doesn’t show the same pressure as my Fine Offset console

Cumulus displays atmospheric pressure corrected to sea level. The console calls this ‘relative pressure’; it displays the letters "rel" when this is being displayed. First of all, check

  1. that you are comparing the Cumulus display with the ‘relative’ pressure on your console,
  2. that only one copy of Cumulus is accessing the weather station (and no other software),
  3. that you do not have a 'EWpressureoffset=x.y' line in the [Station] section of cumulus.ini,
  4. and that you do not have a setting for pressure on the Cumulus calibration screen.

The Fine Offset stations only store absolute/station pressure readings in their weather memory locations updated with each transmission and read by Cumulus. Within Cumulus, the software applies the adjustment to sea level before any further processing. It does not use the altitude setting in the cumulus station configuration screen. Normally when Cumulus starts, it reads in the fixed block in the console a pair of absolute/station pressure and relative/sea level pressure readings and uses the difference between these as the ‘offset’ in millibar for the station; Cumulus uses this offset subsequently to calculate the sea level pressure (each time when reading the absolute pressure in the weather memory locations of the station), but it is possible to define the offset in Cumulus.ini_(Cumulus_1) instead.

IMPORTANT These notes apply to Cumulus 1. bvs79669 did some investigation in January 2019 that reveals the mapping of memory bytes to pressure, reported by Jim Easterbrook, and used by Steve Loft is wrong. The two most significant bits included in that mapping as being part of the pressure output should not be included as they create impossibly high readings for pressure.

Make sure that you have set your console's relative pressure correctly:

  • for a push button operated model, press 'menu' key 4 times for pressure mode, press 'enter' to move to relative pressure setting, press 'up' or 'down' to adjust value.
  • if your model uses a touch sensitive screen then it is probably tap the reading three times, then touch '+' or '-' to adjust value.

The support forum includes discussion on where to find isobar charts or other sources to determine what the pressure should be - make sure you use a reliable source of data, e.g. a Met Office station if in the UK. Obviously after any adjustment you need to stop Cumulus, because it is when you restart it that Cumulus reads the new pressure offset.

Sometimes the offset that cumulus reads from the fixed block is clearly garbage, so

  1. the cumulus error light is set  ,
  2. an error message suggests you check the station, and
  3. Cumulus uses zero offset instead as a best effort.

In this situation, Cumulus will display the same value as the 'absolute' pressure on the console (no "rel" is displayed on the console when it is displaying absolute pressure). Often, if you restart Cumulus, it will then be able to read the correct value. If the problem happens often, you can circumvent it by editing cumulus.ini (while Cumulus is stopped), and in the [Station] section add an entry:


where x.y is your pressure offset. Cumulus will then use this instead of reading the fixed block offset from the station.

Note that you must supply the offset in hPa (i.e. the millibar units that the station works with) and that this circumvention generally stops Cumulus from agreeing with the relative pressure displayed on the console.

If you swap from Cumulus 1 to Cumulus MX, remove this pressure offset, the latest release of MX is much better at communicating with a Fine Offset weather station and rarely needs use of this offset.

My pressure suddenly dropped! Or suddenly increased!

If you have a Fine Offset station, and this happened when you (re)started Cumulus, it is quite likely a problem with reading the pressure 'offset' from the station. See: "Cumulus doesn’t show the same pressure as my Fine Offset console" above.

I get an error when I try to view my all-time records. Also, they don’t appear on my web site

The date format on your system has probably changed. If you look at alltime.ini, you may spot the date format differences and work out what was date of change. Otherwise, go into Control Panel on your PC (not "Settings" as is normal for Windows 10 Operating system) and open the Clock and Region section. Next choose Region option. On the "Region pop-up-screen" you should check what is shown in the Format box, and what is shown in Short date and Long date drop downs.

Please see Correcting_Extremes page for further advice.

I get an error when I close Cumulus

Cumulus 1 does sometimes report an error when you close it. This does not appear to cause any problems, you can just close the error message. I don't seem to be able to do anything about this, as the 'crash' is not in code that I have control over. You may be able to avoid this error by avoiding closing Cumulus while it is uploading to the internet. Please don't bother sending me a bug report about this.

My forecast says "Not available"

You can get Cumulus to create a simple forecast by selecting 'Cumulus Forecast' on the Stations Settings screen.

My forecast always says "Exceptional Weather, Stormy, much precipitation"

You probably have incorrect Pressure Extreme settings in the Forecast section on the Station Settings window. Make sure that the values you have supplied match the units you have selected for the extremes. Note that the units for the extremes are not related to the units you have chosen for pressure display in Cumulus. The option of supplying mb/hPa or inHg for the extremes is merely a convenience; you can supply either, but the values and the units must of course match.

My computer hibernated/suspended, and I lost data/my graphs 'flat-lined'

  Cumulus can't cope with being suspended, it just carries on as normal after being woken. There is an option in the station settings to 'close on suspend', so Cumulus will close itself as a safety measure, if you forget to do it manually. Don't use the 'close on suspend' option and the 'confirm shutdown' option at the same time; this will cause problems.

But I strongly recommend that you don't have your computer set to go into any form of standby while Cumulus is running - it's continuously gathering real-time data, after all, so it's a rather strange thing to do.

My heat index/humidex/wind chill is the same as my temperature

  • These can only be calculated when you have not only your temperature sensor working, but also your humidity sensor must be working for humidex and heat index; and your wind speed sensor must be working for wind chill
  • Wind chill only applies when the average wind speed is above 4.8 kph and (by default in Cumulus as it should really always be set, but this is an option that can be unset) the temperature is below 10 degrees Celsius.
  • Heat index only applies when the temperature is above 27 degrees Celsius and the humidity is above 40%.
  • Humidex does not have any 'cutoff' values, but at low temperature and/or humidity it will give the same figure as ambient temperature.

If heat index or wind chill is not applicable, Cumulus will set them the same as the ambient temperature. You may wish to use a script on your web pages to set to null heat index, humidex and wind chill when required sensors are not working or when the measure is notapplicable.

Cumulus is showing a different wind speed compared to my console

You have probably misunderstood Cumulus processing of wind speeds, looking at different parameters, or different averaging periods.

Note that you can't compare the graphs drawn by Easyweather and Cumulus unless you are certain that they are plotting the same data. They can't both be running at the same time, so one would normally be plotting 'live' data at a given interval, and the other will be plotting data downloaded from the station's logger. The wind speed will hence not normally be the same for a particular time on the graph as it may well have changed at the point that it is saved to the logger. The only situation where it would be valid to compare the graphs would be if neither were running at the times you are comparing, and both subsequently downloaded the same data from the logger.

I get error -32710 with Cumulus and my USB Davis station

The USB support in the Davis DLL which Cumulus uses doesn't seem to work. You need to use the CP210X USB/serial software which Davis supply, and use the station in serial mode. If you have previously been using your station with Weatherlink in USB mode, you will need to change to serial mode in Weatherlink before you can use the station with Cumulus. You can do this using this utility from Davis. See also this FAQ entry -

When I start Cumulus, the graphs restart again each time and don't show the earlier data

 You probably have an error in one or more data files. Look near the beginning of the latest file in the sub-folder called 'diags' for an error message which will tell you which file is in error and which line is causing the problem. It may simply be a blank line. Edit the file with Cumulus stopped. Note that you may need to repeat this process; only the first error is shown.

This problem can also occur if you change your system format settings (date format, decimal and list separators etc). Again, check the diags file for a message about a number not being a valid floating point value.

The peak values on my graphs are not the same as my extreme values

 The graphs are snapshots of the data, taken once a minute while Cumulus is running; it is not feasible to plot every data point. If the extreme value did not coincide exactly with the point at which the data was added to the graph, then it will not appear on the graph. The graphs are not intended to show all of the highs and lows, they are there to give an idea of the trends. This also applies to 'Select-A-Graph', which takes its data from the data logs; the highs and lows do not necessarily appear in the periodic data logs.

This is most noticeable with wind gusts, the value of which can change rapidly, even over a period of a minute. The 'Plot latest gust' setting causes the 'Latest' figure (as shown on the main screen) to be plotted. What this figure represents exactly depends on your weather station type. This figure may vary rapidly, e.g. on Davis stations, it changes every 3 seconds or so. The graphs are plotted once a minute, and hence, with Davis stations, for example, there is approximately a one in 20 chance of any given 'latest' figure actually being plotted.

Cumulus also stores the peak value of the 'latest' figure from the last 10 minutes. It calls this the 'gust', as this is a reasonable representation of a true 'gust' figure. If you untick 'plot latest gust', it will plot this figure instead. As it contains the peak figure from the last 10 minutes, and the graph is plotted once a minute, plotting this value means that the high gust figure will always appear on the graph. The exception to this is with Davis stations, in the situation where the 'high gust' figure has been read directly (as a way of ensuring that the high gust isn't missed) rather than by the usual reading of the current data. In this case, the gust is recorded as the high, but is not written to the current value, and hence does not appear on the graph, as it may be out of sequence with the current data.

My extreme values do not appear in the 'monthly' data logs

The data logs are snapshots of the data, taken at the configured interval while Cumulus is running (or at the station's configured interval when data is read from the station's logger directly into the Cumulus monthly log). Cumulus, while it is running, reads the station frequently, detecting each change in observations, and can update extremes at each of these reading times.

If the extreme value reading time did not immediately precede a time at which the data was logged, then it will not appear in the log. This is most noticeable with wind gusts, the value of which can change rapidly between log entries.

Cumulus is designed to be kept running, if you only run it once a day, then the information it reads from the station's logger during catch up may miss extremes. For example when Cumulus reads the archive temperatures from a Davis station, (in a compromise to allow Cumulus to have as much code as possible that is common to all weather station types) the design means that it ignores the first and second figures representing highest and lowest reported at each logged time, just reading the third figure that, depending on console configuration, is either the average value over the archive period or the final reading of the archive period (I don't know what the default is).

Cumulus takes a long time to download the data from my Davis station at start up

When Cumulus starts, it asks the station for all the data from the logger since the last time it was running. If the time-stamp that it supplies does not exactly match the time-stamp of an entry in the Davis logger, the station has a strange 'feature' where it decides to send the entire contents of the logger. This will take some time to download, during which the Davis console display may appear to freeze.

  1. It is recommended that you enable the feature Synchronise station clock in the 'Settings' block accessed from the Configuration menu Station Screen.
  2. It is recommended that you set the logging interval in Cumulus (in the 'Data log interval' block accessed from the Configuration menu Station Screen) to the same interval as the station (the station interval can be changed using Weatherlink), then Cumulus will be able to make sure it uses a time-stamp that matches an entry in the logger. Note that this is mentioned in the readme.txt file that appears during the Cumulus installation, which you were asked to read at the time. If you didn't read it, it is strongly recommended that you do so now; it contains important information.

Note that this situation can also occur if you close Cumulus and then start it up again very soon afterwards, for similar reasons. There is nothing that Cumulus can do about this, it is an issue with the logger (or Virtual VP, which behaves in the same way).

Davis to Cumulus skips one logged set of readings

The Davis DLL which Cumulus 1 uses never downloads the latest archive record. Consequently, if you have Davis and Cumulus set to logging every five minutes and restart Cumulus at 07:33, the archived readings up to 07:25 will be read across to Cumulus, the set of readings stored on Davis at 07:30 will be skipped, and Cumulus will create its own logs from 07:35 onwards.

My Davis console clock is not exactly the same as my PC clock, but I have "Synchronise station clock" selected

The Davis protocol only allows hours and minutes to be set, so there is always likely to be a difference of up to 60 seconds between the PC and the station.

Today is the shortest/longest day, but Cumulus says that tomorrow will be a few seconds shorter/longer

The routines I use to calculate (at midnight GMT) the length of the day aren't really suitable for this level of accuracy and may use the previous day in one parameter. I don't consider it an issue.

(Also remember that due to refraction affecting route of sunlight to earth, the official equinox is usually a couple of days after when day and night are actually equal).

Cumulus got the forecast wrong!

Cumulus uses a forecast based on the Zambretti Forecaster (see Google). I didn't design the algorithm myself and to be honest I don't know how it works, so I can't answer any questions about it. Note that this is a 'forecast' for the following 12 hours or so; it is not a 'nowcast' (what the weather is doing now). Please regard the forecast as 'for entertainment purposes only'. Do not base any decisions on it, and bear in mind that it is a very simple calculation based on only a few basic parameters. Some people get reasonable results, others do not. You can try tweaking the pressure extreme settings (in the Forecast section in the station settings), but don't expect the forecast to be as good as that provided by the weather agencies which have invested millions in their forecasting systems.

I only see one set of points on the wind direction graph

This happens just after you restart Cumulus, if the data came from the weather station's logger (i.e. Cumulus hasn't been running for a while). Weather stations only supply a 'current' direction, and Cumulus calculates the average direction when running 'live'. So there is only one set of data available to be plotted, if it comes from the station logger.

My average wind bearing remains at zero

Cumulus will always show zero average bearing when the average wind speed is zero (it can't be otherwise because it's calculated using the wind speed). In addition, it will show zero current bearing when the current wind speed is zero if you have use bearing zero when calm selected in the station settings (accessible from Configuration menu).

This also happens if your anemometer has a fault.

My graphs appear to be plotted less frequently just after Cumulus starts up

 When running live, Cumulus plots data at 1-minute intervals. When it starts up, it pre-fills the graphs with data from the log files, which generally (depending on how you have Cumulus and your station configured) will be at less frequent intervals.

I closed Cumulus, the 'please wait' form appeared, but Cumulus didn't close, even after several minutes

 If you've closed Cumulus shortly after it has downloaded a lot of data from the logger, it can take a while for the logging thread to get everything written away to disk, and Cumulus won't close until this has completed. However, in some circumstances, there seems to be a situation where Cumulus will never close, so you will need to close it with task manager. If you think you know what conditions cause this to happen, please let me know.

Cumulus isn't logging data at the interval that I set

It logs data at the interval you have configured, while it is running. If there is data to read from the station logger at start up, each logger entry is logged to the Cumulus log files, so those entries will be at the logger interval that you have configured in your station.

Cumulus takes a very long time to shut down

 You may have closed it very soon after starting it up, when it had a lot of data to download from the station logger, and you use Weather Underground. From version 1.9.1 there is a facility where it 'catches up' with data that hasn't been uploaded to Weather Underground while it hasn't been running. This takes a little while, and if you close it while it is doing it, it will take a long time for all of the updates to time out. You need to give it sufficient time to finish the upload. From version 1.9.2, there is a 'catch up' light which shows that the upload is taking place, and the 'catch up' is optional'; and it will abort much more quickly if you still close it while the catch up is taking place.

My temperature Min/Max/Avg graph is empty

  The most likely explanation is that you have only recently started running Cumulus (in the last day or two). It adds new values to this graph at the end of each day; it wouldn't make sense to add a value part of the way through the day, and you need a few points to be plotted before the graph starts to take shape. You need to wait until you have been running Cumulus for a few days.

If you've been running Cumulus for more than a few days, but the graph is still empty, the most likely explanation is that it was unable to read your dayfile.txt file. Look at the latest file in the 'diags' folder (the files are plain text) for error messages mentioning dayfile.txt.

The longest dry/wet spell for this month/year includes days from last month/year

This is intentional. I decided that it didn't make sense to arbitrarily chop off a dry/wet spell at the start of the month/year, as then the figure is meaningless. So the figures are to be interpreted as "the longest dry/wet spell which includes this month/year". I note that other software takes the same approach.

Cumulus isn't performing periodic tasks, like data logging or web uploads

 Cumulus assumes a certain level of weather station functionality. It checks that it has received data from a number of sensors (e.g. pressure, outside temperature, wind) before it starts periodic calculations, logging, uploading to the web, or drawing graphs. If any of these stop, the previous value will be substituted, for up to 6 readings, then Cumulus 1 will stop working correctly. The reading interval depends on weather station being used, but Cumulus will always read at least once a minute, so it can keep going for just 6 minutes.

This is an attempt to make sure that bad data is not logged. If your weather station is not fully functional, you will not be able to use Cumulus fully.

You can over-ride the start up check by adding a line to the [Station] section of cumulus.ini, thus: NoSensorCheck=1 (You need to do this while Cumulus is stopped). Note that you are likely to get bad data logged if you do this.

NOTE: In Cumulus MX, you can now set the No Sensor Check value from the GUI. See... Station Settings | Common Options

I've changed my Twitter password, and now Cumulus won't update Twitter

  You need to force Cumulus to re-authenticate with Twitter. Stop Cumulus and edit cumulus.ini. Find the [Twitter] section, and delete the lines which start



Start Cumulus and it should be able to update Twitter again.

This also applies if you want to change to a different Twitter account.

When I start Cumulus, I get the error message "The station is not initialised"

For Fine Offset stations, when Cumulus starts up, it checks the first two bytes of the station's memory. They are supposed to contain the values Hex 55 and Hex AA to indicate that the station has initialised itself correctly. If they do not, then presumably the station has had some kind of internal problem, so Cumulus doesn't try to read any data from it. A reset of the station normally fixes this - remove the batteries and the USB cable; but note that you will almost certainly lose any stored data in the logger.

If you want to force Cumulus to ignore this check (not recommended), edit cumulus.ini and add a line to the [Station] section: EWdisablecheckinit=1

You will most likely not have any success with this, as your station memory is probably corrupted anyway.

Note that for this setting to work, you need to be using version 1.9.3, build 1034 or later.

How do I correct today's or yesterday's highs and lows?

If the problem occurred because Cumulus wasn't able to download the data from the station's logger when you started it up in the morning (or perhaps you turned off the 'use data logger' setting for some reason), you can get it to try again by 'rewinding' to the time when you started Cumulus, and allowing it to try again. Cumulus takes a copy of the current files each time it starts up, and puts them in a folder in the backup folder in the Cumulus installation. Both flavours of Cumulus also take a copy of all files as a new day starts and store those in a folder within the sub-folder daily (within folder backup).

To do a rewind:

  1. Stop Cumulus,
  2. find the backup folder with the appropriate timestamp,
  3. copy all of the files from the backup folder into the Cumulus data folder,
  4. start Cumulus up again.

Today's totals, highs and lows (and yesterday's rain total) are held in today.ini in the Cumulus data folder. Follow the cross-references if you are unsure which parameter is what. To change any values, stop Cumulus and edit the file(s) in a text editor. Be sure to keep any date and time formats the same.

If you are editing yesterday's highs and lows, the totals (including RG11 rain but not standard rain), highs, and lows are held in yesterday.ini. However, you probably also need to read Amending_dayfile, as many of the values should have been written to dayfile.txt file.

If your all-time and/or monthly all-time records have been affected, see the next FAQ entry.

If the value you want to change is today's high hourly rain figure, it is best to wait until the current figure has returned to a sensible value. There is no easy way to correct the current figure, so if you change it in today.ini while the current figure is incorrect, the high value in today.ini will immediately be changed again when you start Cumulus. More information about correcting rain in this FAQ.

How do I correct my all-time (or monthly all-time) records?

Cumulus works by whenever the reading it is currently processing exceeds a particular extreme record, that record is updated. It cannot make any adjustments retrospectively.

Cumulus takes a backup of most of the active data files when it starts up, and also at the start of the meteorological day (just after midnight for a lot of users). The backups are kept in folders within the backup sub-folder in the Cumulus installation. So often the easiest method would be to find the latest backup from before the error occurred, and copy the alltime.txt and/or monthlyalltime.txt file from the backup to the Cumulus data folder. Do this with Cumulus stopped.

There is advice on Correcting_Extremes page that explains how corrections can be made. Using the Cumulus 1 built-in appropriate editor from the first couple of commands in the Edit menu allows you to see, and copy across, suggested extremes based on contents of the monthly Standard_log_files or contents of the daily summary log.

If you know the correct figures, you can alternatively enter them manually directly into the .ini files and not bother to update the detailed log or the daily summary log. (It is pointless to edit the .ini files directly and then afterwards edit the log files):

It's January 1st and my 'rain since midnight' and/or 'last 24 hours rain' and/or Evapotranspiration are wrong/negative

You are probably using a Davis station. Cumulus needs an incrementing rain counter to calculate all of the rain figures, and the nearest to that on a Davis station is the annual total. When this resets at the end of the year, this causes some of the rain data to show odd values for a day. You will notice this particularly if you use an 0900 start of meteorological day, as the 'rain since midnight' figure is used for services such as Weather Underground. There's no easy solution to this, sorry.

Cumulus stops at the "Downloading data" screen

  If you have a Fine Offset station, this is probably caused by the station's USB interface locking up - a known problem with some Fine Offset stations. You should be able to get it going again by doing a reset - remove batteries and the USB cable. Recent Fine Offset models have a problem where they can lock up frequently, requiring a reset. From version 1.9.3 of Cumulus onwards, there is an option to synchronise the reading of data with the console writing the data, to avoid doing both at the same time, and this seems to avoid most lockups. The setting is "Synchronise Fine Offset reads" on the station settings screen.

If you look in the status bar at the bottom of the Cumulus window, there may a message "Error: no response"; this would confirm that the station has locked up and needs resetting.

If you are using the "Synchronise" setting but are still getting frequent console interface lockups, then the clocks on the console and the platform running Cumulus may be drifting too far between synchronisations. Look in the diags_folder files for the word "drift" and see how many seconds apart the clocks are drifting. If it is more than 3 seconds, you will need to adjust the period that Cumulus allows where it doesn't read the console data. Stop Cumulus and edit Cumulus.ini_(Cumulus_1). In the [Station] section, add a line:


where N is the required setting in seconds. If you find you are getting a drift of 9 seconds, say, you might set the value to 10.

Cumulus locks up when it starts and I have to use the task manager to kill it

  If you have a Fine Offset station, this is most likely caused by the station's interface locking up, i.e the station has stopped communicating with the PC.

The problem where Cumulus locks up when the Fine Offset station doesn't respond is fixed in version 1.9.4. If you look in the status bar at the bottom of the Cumulus main window, there may be a message "Error: no response"; this would confirm that the station has locked up and needs resetting.

You should be able to get the station going again by doing a reset - either remove console batteries and the USB cable or press the reset button hidden below the small hole (on 1081-based models, above the top RH corner of the battery cover). Recently manufactured Fine Offset models have a problem where they can lock up frequently, requiring a power reset. From version 1.9.3 of Cumulus onwards, there is an option on station settings screen to Synchronise Fine Offset Reads (Cumulus reading data from console) with the timing of received transmissions from sensors updating the data, to avoid doing both at the same time, and this seems to avoid most lockups.

Error messages with "Error on line..." or "Error at line..."

These are corruptions in the log files, typically caused by Cumulus being unexpectedly closed (e.g. killed using Task Manager, or a PC reboot) while it is writing to the log files, but there can be other causes such as power blips or you using a spreadsheet to look at or edit the log file. The error message may say something like "List index out of bounds". The error message will name the affected file(s) and the affected line number(s).

Stop Cumulus and open the named file(s) in a good text editor, such as Notepad++. Do not use Notepad. At the line number(s) mentioned correct the error(s), which will be obvious as the lines won't look like the other lines, they will be blank or have garbage characters, have an extra field that throws other fields out of position, or perhaps two lines have been run together. Save the file(s) and start Cumulus again.

Cumulus gives an error and won't run on my HP computer

  It's a known problem with HP computers; they have missing fonts. One solution is to install this font update from Microsoft. It appears that computers other than HP can have the same font issue, so it is worth installing the font update anyway, if you get a problem where Cumulus won't start.

The headings or data look wrong in the data log viewer

You're probably trying to view the wrong type of file. Use menus on main screen.

"View | Data logs" is only for the monthly data logs, e.g. Oct13log.txt, "View | Extra data logs" is for "extra" data logs, e.g. ExtraLog201310.txt, and if you want to view the daily summaries in dayfile.txt, use the dayfile.txt editor - "Edit | dayfile.txt".

The wind rose in Cumulus does not display anything with my Fine Offset

 The Fine Offset weather stations are supposed to supply data for 16 wind directions, however the design is such that most of them only actually use 8 of the possible 16. Try setting the wind rose to only display 8 directions by setting the 'wind rose points' value to 8 on the display settings screen.

I've set the graph background to white, but there's a problem with the small wind direction graph

This appears to be an issue with the third party chart component. The work around is to choose a gradient background and set all three colours in the gradient to white.

My Weather Underground tabular data interval is not the same as the interval I've set in Cumulus (I'm using Rapid Fire)

If you have selected 'rapid fire', the data is uploaded every 5 seconds, and the interval you configure in Cumulus is not used. Weather Underground decide how often your tabular data is logged when using rapid fire, not Cumulus.

My WU or PWS highest and lowest do not match Cumulus

Note that Cumulus does not send minimum and maximum values to PWS and WU, they determine those themselves from the individual values that Cumulus sends.

My monthly (month-by-month) all-time records don't have entries for all of the months that I have been using Cumulus

You need to initialise them. See the release announcement for version 1.9.3, which is when this facility was introduced:

You only need to do this once; when you have initialised them, Cumulus will keep them up to date thereafter.

I am getting I/O error 32 or I/O error 103

I/O error 32 = ERROR_SHARING_VIOLATION;   I/O error 103 = 'file not open' mean something on your system has one of the Cumulus files open, preventing Cumulus writing to it (Cumulus needs exclusive access). If you are seeing "file access denied", you may have a permissions problem. Possible reasons for locked files:

  1. Anti-virus, or back-up, software scanning/accessing the file (this is the cause in almost all cases that I've seen).
  2. An edit or file transfer in progress (the Cumulus thread for logging and the Cumulus thread for FTP are independent so can overlap). This is likely to happen if you are getting Cumulus to frequently upload the log file to your web site.
  3. Some other software that a user is running which is processing the file in some way.
  4. More than one instance of Cumulus running (see #Can_I_run_2_copies_of_Cumulus.3F).
  5. An issue with the system clock on the PC.

I have problems after upgrading to Windows 10

 See this forum post -

How do I enable debug logging in Cumulus?

This depends on your build:

  • The only way to turn on the logging of debugging messages in all builds of Cumulus 1, is to stop Cumulus 1, edit the Cumulus.ini_(Cumulus_1) configuration file, and add a line in the [Station] section: Logging = 1, then restart Cumulus 1.
  • From build 1003 onwards, you can also turn it on/off using the Configuration menu (debug option is included in drop down of that menu).

Please see all these pages: Bugreport.txt, Debug.log, and Diags_folder.


How do I set up a website?

The crucial settings are selected on the Internet screen in the Configuration menu.

  • On the Sites/Options tab, you must have Auto Update selected if you want Cumulus to generate web pages at the standard interval. Other parameters will depend on your particular set-up, but are explained in the Cumulus Help and in Wiki pages starting with Website_setup and following links as required.
  • On the Files tab, you select whether to use the standard Cumulus templates and images, or specify your own templates and destinations.

I’ve configured my ftp details but the web pages aren’t appearing on my site

Try setting ‘use active FTP mode’. If you already have it set, try unsetting it. If it was previously working OK, something may have changed on your network, or at the server end.

I’ve tried active FTP mode, but my web pages (or my realtime.txt file) still don’t appear?

Are you absolutely sure you have set the ftp path correctly? Most problems like this are a result of an incorrect path. Note that the information in the 'FTP progress' window is not generally useful for diagnosing upload issues' try turning on the ftp logging (on the Configuration menu) and look in the ftplog.txt and realtimeftplog.txt files (in the Cumulus folder). It is best to supply a relative path - i.e. with no leading 'slash'. Please don't ask me what path you need to supply, it is impossible for me to guess how your web space is set up. If you cannot work it out, ask your web space provider for help.

How do I replace the 'bird' image on my website?

There are several ways to change the image of the 'bird' on the standard Cumulus web page. You will need a FTP tool.

  • The simplest way is to upload a new picture to the images folder of your website; the file should be called picture.jpg. Please ensure the image is not too large and bear in mind it will appear on the bottom left of the page; the site data may cover some of the image. As a guide, the default image is 600 x 450 pixels.
  • Secondly, you may upload an image using your own file name. Edit the weatherstyle.css file and look for the line background-image: url(images/picture.jpg); around line 9 and adjust as necessary. Upload the edited css file to your website.
  • if you wish to remove the image completely edit the weatherstyle.css file and remove the line background-image: url(images/picture.jpg); Upload the edited css file to to your website.

NOTE: It is not recommended that you overwrite the image in your local folder (webfiles\images\picture.jpg) because that gets overwritten when you update to a new build of Cumulus. Ideally your image will be in its own local folder outside the Cumulus structure.

Why does the heading say 'weather weather' ?

The standard first template page contains <h1><#location> weather</h1>, so do not include 'weather' in your station name (this is what the tag <#location> represents, see next answer) to avoid it being duplicated.

How do I change the "Welcome to." on the front page

The Welcome message is controlled within Cumulus. Click on the Station screen in Configuration menu and Edit the Description field within the Location frame to amend what the tag <#longlocation> represents in "Welcome to <#longlocation>." on template page.

I don't have a solar sensor. How do I remove the solar data from the supplied web templates?

Locate the Cumulus 'web' folder on your PC and edit the following files (there are comments in the html to guide you):


Remove the following code:

  <!-- Solar data. If you don't have a solar sensor, you may wish to delete everything from here to the next comment -->
  <tr class="td_temperature_data">
    <td>Solar Radiation</td>
    <td><#SolarRad> W/m²</td>
    <td>Evapotranspiration Today</td>
    <td><#ET> <#rainunit></td>
  <!-- End of solar data -->


Remove the following code:

    <!-- Solar data. If you don't have a solar sensor, you may wish to delete everything from here to the next comment -->
    <tr class="td_temperature_data">
      <td>Hours of Sunshine</td>
    <!-- End of solar data -->


Remove the following code:

    <!-- Solar data. If you don't have a solar sensor, you may wish to delete everything from here to the next comment -->
    <tr class="td_temperature_data">
      <td>Hours of Sunshine</td>
    <!-- End of solar data -->

How do I remove Inside Temperature graph, or add solar/UV/sunshine, to Trends Web Page?

 BELOW ONLY APPLIES TO CUMULUS 1. Locate the Cumulus 'web' folder on your PC and edit the following file: trendsT.htm

Modify the following code:

    <td class="td_thumbnails"><a onclick='changeImage("images/intemp.png")'><img src="images/intempsm.png" alt="Inside Temperature Graph Thumbnail" width="150" height="100" style="border:0" /></a></td>
  • To simply remove Inside Temperature graph, change code above to this
  • If you want to stop Cumulus uploading the indoor temperature graph, you can un-tick 'Include standard images' on the 'files' tab of the internet settings, and list all of the images that you still want to be uploaded as extra files. Cumulus 1 configuration only allows you to add 10 files so you would need to do this by editing Cumulus.ini_(Cumulus_1), ironically these notes do not apply to Cumulus MX but in that all 100 slots can be edited within the settings pages.
  • To show solar instead, replace 'intemp.png' with 'solar.png', replace 'intempsm.png' with 'solarsm.png', and change the wording of the value associated with the alt property.
  • To make Cumulus upload the solar graph, select it on the 'files' tab of the internet settings.
  • To show sunshine instead, replace 'intemp.png' with 'sunshine.png', replace 'intempsm.png' with 'sunshinesm.png', and change the wording of the value associated with the alt property.
  • To make Cumulus upload the sunshine graph, select it on the 'files' tab of the internet settings.
  • To show UV instead, replace 'intemp.png' with 'uv.png', replace 'intempsm.png' with 'uvsm.png', and change the wording of the value associated with the alt property.
  • To make Cumulus upload the UV graph, select it on the 'files' tab of the internet settings.

If you want to do more than a straight one for one swap see customisation page here.

How do I include extra items on supplied web templates?

Open the folder cumulus\web and edit the relevant file named xxxxxT.htm. For example instead of deleting the sections in the remove solar answer, edit their contents. See Customised_templates#Changing_the_Standard_Templates for fuller description.

If you do change the standard templates, take a copy of your new versions, and store elsewhere. The sub-folder cumulus\web\originals has copies of the standard templates from the installed build, do not edit these. When you install a new build of Cumulus, you have an option to replace or not replace the contents of cumulus\web with the new build's standard templates.

How do I upload extra web pages?

See Cumulus help for the Internet Settings screen, or for a step-by-step guide see Customised_templates#What_to_select_on_the_.27Files.27_tab_of_the_Internet_Settings_screen_within_the_.27Configuration.27_menu

What character encoding does Cumulus use for the web pages it generates?

Cumulus 1.9.4 build 1093 changed all the template pages from XHTML 1.0 Transitional using charset=iso-8859-1 encoding to HTML 5 using charset="UTF-8" encoding. It uses this without Byte Order Mark (BOM).

From that build, you can tell Cumulus which of those two encodings to use:

  • For standard template names in standard 'cumulus\web' folder, if you replace them with customised templates not using "Universal Character Set Transformation Format — 8-bit" (UTF-8),
    • unselect UTF-8 encode in the web settings frame on the Sites/Options tab of Internet settings screen in Configuration menu.
    • Cumulus will then, as in earlier builds, use iso-8859-1 encoding.
  • For extra templates, the Files tab of the Internet settings screen in Configuration menu has the option to choose which of the two Cumulus encodings to use. See Wiki article referenced in previous answer.

Note that since Cumulus 1.9.4 build 1078 there has been an option on the NOAA Setup screen in Configuration menu to specify whether character set utf-8 encoding is to be used for those reports.

Why does a standard gauges web page have text where it should show gauges?

    If a standard Cumulus 1 'gauges.htm' web page displays like this then either

1) (Most Likely) The weather station owner has not loaded the required files/folders onto his/her server;

  • The gauges graphics require the 'images' subfolder (see next answer), containing the script and many images to be pre-loaded in the 'dbimages' subfolder.
  • All these should exist within the destination folder that holds the HTML files as instructed in the Cumulus Help ('setting up your website' page)
  • Also explained in Simple Website setup on this Wiki.

or 2) JavaScript is not enabled (or not available) in the browser being used to view the page (if not enabled, this can be switched on in either 'Options', 'Preferences' or 'Settings' depending on browser). Note that Firefox from version 23 removed the ability to change this in Option preferences, so ignore this solution in that browser.

or 3) You are using a browser add-on such as 'NoScript' (over 2 million use this) which requires you to explicitly turn on JavaScript for each web site you visit within the 'NoScript' options. (This sort of add-on may be used to restrict advertising or tracking of your actions, or for security against unwanted processes being started by sites you visit).

Why are there no graphs on my standard trends web page?


Either 1) You have not created an images sub-folder (within your folder that holds web pages) as instructed in the Cumulus Help ('setting up your website' page) - also explained in Simple Website setup. In this case, the bird image will not be appearing in the bottom left corner of your web pages.

Or 2) You have switched off Include Standard Images on the file tab of the Internet dialogue of the configuration menu. In this case Cumulus believes you are working in a non-standard way, and does not automatically upload the graphs (nor moon image).

What is the size of the standard Cumulus update?

 The default is that all of the standard pages and standard images are uploaded on each update at whatever standard update frequency you select.

In total for version 1.9.2, it's about half a megabyte - about 100kB for the pages (about half of that is the gauges.htm page with all the detailed wind plotting points, and half the other pages) and 400kB for the variable images (moon phase, some gauges images and trend graphs - the exact size of latter can vary if you change the period they cover).

Version 1.9.3 adds the monthly records page which contains 12 months worth of a lot of data, and adds 25kB to every update (although usually very little changes between updates).

The NOAA monthly and annual pages are uploaded once a day, that is another 8kB for a full month and full year, obviously less at the start of a month/year.

Optional extras

  • realtime.txt file, this is less than 1kB (1024 Bytes) in size.
  • dayfile.txt a file that is about (30 times number of years) kB
  • The files required to update external sites are no more than a few kB.

How do I upload my own pages or files once a day?

Cumulus allows you to specify a command (with optional parameters) that will be actioned just after daily rollover. The command is entered in the External programs frame at the bottom left of the Internet Settings screen. The box is labelled Daily. Click the Cumulus Help button for guidance. For example you could type 'c:\cumulus\daily.cmd' in the box labelled Daily.

This could be used to upload the pages with the longer term extremes (as your monthly, annual and all-time extremes may only change a few times a month or even less frequently) and so reduce the upload burden at the standard uploading frequency. To achieve this you would use the content of that example file 'daily.cmd', in the default Cumulus folder, to call your own file transfer tool for those infrequently changing pages. Remember to also unselect Include Standard Files on the 'Files' tab of 'Internet settings', and list the templates on that tab, selecting Process? for all of them, but only selecting FTP? for the other frequently changing pages that are still to be uploaded at the standard interval. You may find help on the forum or elsewhere on this wiki for the FTP call and for 'Files' tab settings.

It can also be used for the optional files mentioned in the previous answer or to update a database using a PHP batch job. For the daily command specified above, in the default Cumulus folder, add a file 'daily.cmd' that contains (if you host your own server using 'XAMPP'), 'copy c:\cumulus\data\dayfile.txt C:\xampp\htdocs\weather\daj\' for example to enable you to use the Annual Day-by-day Summary tool. (Uploading if you do not host your own server is described at upload dayfile but basically you swap the copy command for a FTP command).

The 'real time wind data' gauges on the standard gauges page aren't working

These require a realtime.txt file to be uploaded by Cumulus. Tick the "Enable Realtime", "Enable Realtime FTP" and "Enable realtime.txt FTP" boxes on the internet settings screen. If the gauges still do not work, check that the realtime.txt file is being uploaded to the correct place. If it is not, it is likely that you have specified an incorrect 'ftp directory' in Cumulus. If your 'normal' pages are being uploaded correctly, but realtime.txt is not, then it is likely that you simply need to leave the ftp directory blank (but see the note below first).

A possible cause for this problem is that your web space provider does not allow .txt files to be accessed. For example, the free hosting provider do not.

I'm using the supplied web pages, and get lower case in places where I want upper case

It's in the CSS. Go to the webfiles sub-folder of your cumulus installation, edit weatherstyle.css and find lines like: "text-transform: lowercase;" and remove them. Use FTP tool to replace the weatherstyle.css on your website.

My web pages have things like <#location> in them

You’ve edited your templates with something like Dreamweaver, and it’s changed the angle brackets on the Webtags to "&lt ;" and "&gt ;" - you need to change them back to < and >. These may look the same when viewed in your browser, but you can see the difference if you 'view source'

Alternatively, if the web templates are listed in cumulus.ini (and for the first 10 appear on the files tab of Internet dialogue of Configuration menu), the Process option must be ticked for the web pages generated by Cumulus to have values replacing the Webtags. Otherwise at each web update, Cumulus will generate web pages the same as the templates.

My web pages are empty

One common cause of web pages appearing to be of size zero, or not uploading with new contents when Cumulus attempts to use FTP, is that your firewall (or your FTP server) has limited the allowed operations (e.g. can't delete, can't insert, can't rename ...). Try changing from passive mode to active mode transfers (or vice versa). Try using a manual FTP operation (with your own FTP client) and see if that works.   If empty web pages are being successfully uploaded to your web site (i.e. they report size of 0 kB, but do not produce 'error 404 - page not found' message), and your browser shows that their modification date is recent (see next FAQ), then another likely cause is that the Cumulus processing of templates is failing:

  • Either (since build 1093, as made clear in the release notes)  the character encoding (for standard named templates that are processed by Cumulus) is specified incorrectly on the Configuration menu, Internet dialog, Sites/Options tab, Web Settings frame as shown about half way down on this screen extract:
    • Select the option where indicated by red arrow if your template includes in a line near the start <meta charset="UTF-8">
    • Deselect the option where indicated by red arrow if your template includes something like <meta content="text/html; charset=iso-8859-1" http-equiv="Content-Type" />
    • For customised pages, (without standard Cumulus template names), select/un-select the UTF-8 encoding in the appropriate column on the Configuration menu, Internet dialog, Files tab screen where you list the local and remote names.
  • Or you have edited/customised the template and added an incorrectly specified Cumulus webtags that has caused Cumulus processing to abort for that template. If you stop cumulus you can use a text editor to open the latest diagnostic file. Look at entries time-stamped just before the hour and repeated at your auto-update interval (just below red arrow in screen image above). You might find a message like "Error processing C:\web\indexT" (i.e. mentioning whichever template is at fault) followed by a brief hint as to the nature of the error.

My web pages have obsolete web tag values in them

If the information showing on your web pages is out of date, then it must have been working before, so you have made a change somewhere.

  • Most browsers will display 'page information' that tells you when the page was last modified (by querying the web server).
    • if the page on your web server was recently modified,
      • then the next item to investigate is the template file; a template file contains Cumulus web tags and the 'process' that Cumulus does to create a web page involves reading text from a template and when it finds a web tag it inserts the latest value in as it creates the page. A local file is then created and Cumulus will FTP (or copy) this to the web server according to the settings. If the template file cannot be processed, Cumulus may still upload an existing old local file.
    • if the page was not recently modified,
      • maybe you are not running Cumulus, so it is not updating.
      • maybe your file transfer is not working, turn ftp logging on for technical output, and look for any filenames and any 'successfully transferred' messages.
      • maybe your 'internet settings' screen has accidentally been changed, see Cumulus help for simple instructions. If you took a backup of cumulus.ini you can stop Cumulus, rename the current file and copy your cumulus.ini backup back into the 'cumulus' directory containing the Cumulus program.
      • maybe your web server provider has changed something.

Running a web server on the same PC as Cumulus

If you do not have a web site, or run a web server locally (same PC, or on your local network), you can get Cumulus to generate/copy either html, or image, files locally instead of using FTP to place them remotely.

You'll need to list the (source) file including paths on the files tab of the internet settings, and specify a destination path and file name for the remote file in each case. Don't tick the FTP? box for standard cumulus pages (the exception is for a local web server and any non-standard web page that attempts to read using a script a local file such as dayfile.txt as this does need FTP to generate the server-based web page). For the standard images, you can supply a folder name (specify on the same screen), and they will all get copied there. See here for greater detail.

There's a limit of 10 entries on the files tab in Cumulus 1.9.x (in Cumulus MX all 100 entries are included in the settings interface). Entries for the full 100 files can also be amended by editing cumulus.ini, with Cumulus stopped. Follow the format of any existing entries for specifying additional files.

Error Codes generated by FTP or Winsock

You should be able to look these up on the web. Try Here

How do I configure Cumulus for Secure FTP (SFTP/FTPS)?

Cumulus 1 doesn't support Secure FTP. You can configure Cumulus to invoke an external program like WinSCP, as described here: SFTP article

Directory related problems in FTP

The following pointers should help:

  • All web site file references are case sensitive. So if your FTP server directory is public_html, then 'Public_HTML' will not work!
  • On the Internet settings screen in Sites/Options the optional Directory parameter required is the path from your FTP root, to where the web pages are to be stored. It is not the Universal Resource Locator (URL) that you would specify to view the web page in a browser. Click the Help button for full explanation, or search the support forum (as many people before you have found this directory is the hardest parameter to get right).
  • The error window is not useful for diagnosing ftp problems; you need to turn on ftp logging and look at ftplog.txt. Most FTP directory problems are due to you quoting an incorrect ftp directory, and the ftp log will show an error when an attempt is made to change to the directory you have specified incorrectly.
  • Relative paths (without a leading slash) are always safer than absolute paths (with a leading slash) and you may find that just specifying (for example) "public_html" works OK, but this all depends on how your ftp server and your ftp account is set up.

  • The standard pages are uploaded after a 'change directory' attempting to select the directory you specified in Sites/Options; if this fails, the files will still be uploaded but to the FTP server root. So some mistakes do not matter because if no change of directory was actually required, these pages will be uploaded correctly.
  • Any files you specify for uploading at standard update frequency are uploaded between standard pages (if 'Include Standard Files' selected) and (applies only to Cumulus 1) standard images (if 'Include Standard Images' selected). You should specify the path (including any web site directory) in 'remote filenames', as there is no call to 'change directory'. In this case, if that path is invalid, the upload fails.
  • The standard images for gauges and trends pages are uploaded after the standard pages, (and any pages you specify for uploading), by performing a second 'change directory' this time fixed at 'images'; if this fails, the files will still be uploaded to the current web site directory (FTP root or the directory you specified in Sites/Options).
  • If you have enabled Realtime, the realtime.txt file is uploaded without doing a change directory, (by appending "/realtime.txt" to the directory on the Internet settings screen in Sites/Options). In this case, if the web site directory in your settings is invalid, the upload of the real time file fails.
  • On the NOAA Setup screen the optional Directory parameter required is the relative path; from your FTP root, to where the NOAA report pages are to be stored. (It is totally independent of the directory on the Internet settings screen in Sites/Options). Click the Help button for full explanation. Like realtime.txt, the upload destination is determined by appending the file-name for the report to any NOAA directory, and will fail if that directory is specified wrongly.

See Setting up your website in Cumulus help for a simple guide to the sub-folder structure you need to create and the list of files that need to be uploaded manually when first installing a website. Or see Website_setup for all the options including customised pages.

My standard web pages are uploading but the uploading fails for images, realtime and/or NOAA reports

See previous answer, you have probably got your web pages in the default FTP directory of your web site, but specified the wrong directory on the settings screen. Turn on the FTP logging in the configuration menu to see the technical detail. You should have an FTP tool that you used to upload the 'static' files required on your web site, and that will help you to see what is your site's root directory for file transfer uploads, and therefore any relative directory change you require.

What file-names does Cumulus use when processing and uploading files to my web site?

FTP Process

Cumulus use two slightly different processes depending on if the file is part of the supplied 'standard' web site, or an extra file you have specified on the Internet Settings|Files configuration dialog. For each of these processes there is an further variation depending on whether you have enabled the Use FTP rename option. This graphic shows the various combinations of file-names used for each step of the process. For the standard files, you can substitute any of the file names for indexT.htm, e.g. trendsT.htm

For more details of Cumulus Process see here.

Selecting a Weather Station sensor site

A simple guide is at newsgroup, note this advises against roof mounting. An attempt to compare the conflicting siting standards that apply across the world is included in a portable document format guide from Campbell Scientific. For more advice see the website of your local Meteorological Bureau, an educational place (e.g. in USA see Cornell University), the World Meterological Organisation (WMO), or a specialist organisation (e.g. in UK see Royal Meteorological Society rather than the Met Office web site).

Modern Stevenson Screens are uPVC constructed with a black interior (so they do not radiate heat onto the sensors) and a white exterior (so they reflect as much radiation as possible). There is a lot of discussion on the Homebuilt forum about different approaches to improving measurements, and the problems with out of the box instrumentation from the different manufacturers.

If you are contributing to an external site like APRS/CWOP, Weather Underground, PWS weather, Weatherbug and/or WOW, see guidance from these organisations re instrument placement.

Note: Some stations have all sensors in one unit, positioning of these is a compromise between the ideals below for each sensor.

Where should I position the wind sensors

The side labelled 'North' on the wind vane mount should face True North, remember that the magnetic north deviation from true north varies from year to year, see details on maps or online. Most wind vanes have a large surface that follows the wind and a thin end that points where the wind comes from, it is the latter direction that is reported.

In the UK, the standard climatological measuring height is 10 metres. Advice varies on whether you should apply a correction factor for any lower height. Cumulus allows you to apply such a factor to either just wind speed, or wind speed and gust speed, by using the Calibration screen within the configuation menu. In the Cumulus Help it recommends that you also adjust wind chill - in practice this means ask Cumulus to calculate wind chill by selecting this in the settings frame on the station settings screen accessed from configuration menu (i.e. ignore any wind chill output by your weather station).

If you are mounting near a building of height 'h' above ground level, ideally the wind sensor should be at a height of '1.5 times h' above ground level. If you are positioning away from a building or tree (or other object) of height 'h' (or the mean height of several objects is 'h'), then the distance away depends on which standard you are trying to meet, and can vary between 1.5 and 3 times 'h'.

Where should I position the rain sensor

The WMO says the rain gauge should at a distance away of 2 times the height of each nearby object (buildings, trees, walls, solid fences etc.) and just high enough off ground level to avoid possibility of splashing. You can experiment, but for amateurs, no more than a metre off the ground (or roof if mounted above it) and at least a metre from any chimney, wall or solid fence whose height exceeds that of the sensor seems good enough for most gauges. See Rain measurement or your local offical organisation.

How do I protect my rain gauge against spiders or other natural problems

There is a lot of discussion on the Homebuilt forum. In terms of siting, it is important to position your rain gauge where you can safely get to it.

How do I get good temperature and humidity measurements

The international standard states ambient air temperature/humidity is measured at 1.25 metres above ground level, above soil or grass not paving, protected from direct sun radiation (and direct rain), unless you are measuring soil or ground temperatures. The height is important for derived values as an air frost is defined as a temperature at or below the freezing point for water at this height, and the count of these is a standard reporting requirement in some countries.

If you are using a Fine Offset sensor, the thin depth of the thermometer/hygrometer (transmitter) should face where your console (receiver) is, for maximum transmission strength/distance, with the wide face at right angles to the transmission route. (Although if you use a model requiring a radio time signal, you will probably be trying to optimise that instead).


Varies with altitude and temperature, but no significant variation with spatial position with regard to nearby fixed bulky objects. Often measured indoors, do not mount above any heating or cooling system as there temperature may be particularly variable, and try to avoid any forced ventilation or extraction as such air moving systems could have different pressures on intake and outlet sides. Equally operation in close proximity to opening doors/windows or to fast moving (road or railway) vehicles or tunnels can distort readings.


One would expect solar sensors should be positioned for maximum unshaded exposure to sunlight throughout the year, but again the forum contains advice for specific makes.