Standard log files

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Cumulus Version MX SpecificCumulus Version 1 Specific This page applies to all flavours.


Cumulus has ability to log data on a periodic basis, see Monthly log files:

  • This page is about the standard logging file, that is always created, with a new file in each new month
  • Steve Loft started work, for Cumulus 2 on a replacement for these files using a database, and planned Cumulusmx.db to hold such data for MX 3.0.0 beta, although his work on this was never completed.
  • Other files (Speciallog.txt , Extra_Sensor_Files, and Air_Link_Log.txt) are optional, in that settings determine whether they are created or not.

In fact, in Cumulus MX, the processing of this extra sensor logging file shares a lot of the code with the processing of the standard logging file, as they both are updated at same interval, and they both take values processed following a read from your weather station. The applications programming interface (api) that sends values between the MX engine and the MX admin interface is also identical (with a parameter "Extra" that swaps between true and false depending on the log file involved).

The logging file, speciallog.txt, for detailed logging of internal temperature and humidity is not split into separate files for each month. Although this exists in Cumulus 1, it appears this functionality will remain missing from MX.

The logging file for air link sensors, is only available in MX.

How often is data stored in the standard file?

These store the full set of current (read and derived) values at whatever interval you have set for Cumulus to keep detailed logging.

  • The interval has to be a fraction of an hour, so the least often storing is every half hour.
  • For some weather station types, you MUST match the interval at which the weather station logs data internally
  • The default time interval between adding data logging lines is every 10 minutes, but you can change this:
    • Legacy Cumulus 1: On main screen, select Configuration menu, select the station settings screen, look for Data log interval box on extreme RH side.
    • Cumulus MX: From Interface, find settings menu, select the Station settings page, select General Settings, and find Log interval where there is a drop down that offers the various timings that are permitted.

What name is used for the standard file?

These files are automatically created with names in the form <Month><Year>log.txt.

In UK English locale, the file for August 2009 is called Aug09log.txt.

The month can be in another language, or a different abbreviation, depending on your locale.

The same naming format must be used for all files,if Cumulus is to be able to find them. For Cumulus MX only, any file lines for dates before the Cumulus start date will be ignored.

File content

This file has one line added each time the Cumulus timer says the logging interval has passed.

All data is logged in the units as selected by the user:

  • Cumulus 1: On main screen, select Configuration menu, select the station settings screen, Units box is just below the centre of that screen.
  • Cumulus MX: From Interface, find settings menu, select the Station settings page, and find Units section.
    • Advanced settings in MX allow you to vary the number of decimal places for the various stored values

Each line has a number of fields separated by whatever symbol is defined as the list separator on your device, typically a comma (,) or a semi-colon (;).

  • The various fields are all listed after this section, but they can be of various types:
    • Date, this is always the first field, and it always uses a fixed format, ignoring the format defined in your locale.
    • Time, this always the second field, and is always in the form hh:mm (Cumulus will not be able to understand the file if you edit the time to a format that includes seconds) using the 24 hour clock and local time (system time). However, if you use the feature in MX to upload the equivalent of this file to a database table, the automatic update upload will add ":00" to include seconds.
      • Note that it is perfectly possible to have two successive lines in a standard log file with same time, although this should not happen in normal running, it can result from a hiccup or other interference on your device. If you are asking MX to upload the contents of this file, a second line with same time is ignored, only the first line with a particular date and time is uploaded.
    • All Remaining fields are spot values, either what has just been read from your station, or a derived value calculated from a set of values read from your station. For these value fields, Cumulus may have converted from the unit used by your weather station to the unit that you have requested to use, and there will be some inaccuracy inevitable in such conversions. Where the value to be stored is a real number with decimal places, Cumulus will use a decimal comma or decimal point depending on which is defined in your locale, do be careful not to change that locale if you need to change your device or update it, as Cumulus can only read files where the same decimal separator is used everywhere.

For more information on these files see in the Cumulus help file, in the section “The Data log file”. This is installed with Cumulus 1, but can be read with Windows after downloading from Software#Resources page in this Wiki.

List of fields in the file

The table is split by Cumulus version for all changes since version 1.7.x (Steve Loft did not retain his list of changes in 1.4, his changes.txt is rather sparse in details for many releases, and the support forum excludes any posts before 2 Jun 2008, so earlier changes are not now documented).

The table shows:

  1. The field number
    • When this list was first produced, only the original Cumulus software was available and the decision then was to start with date in field zero to be consistent with index used for arrays in programming languages like JavaScript.
    • In the data log editing page of the MX admin interface, and internally in its code, MX uses field zero for the line number, and therefore the table below has been edited so that date moves to field 1.
    • For each field the equivalent letter that would be seen in a spreadsheet like Libre Office, Open Office, Excel etc is also shown in first column.
  2. As a quick guide to which fields can take signs and which can not accept decimal places, the second column indicates formatting rules.
    • Any item labelled integer will not accept any decimal places.
    • Any item labelled number can in Cumulus 1 take integer or decimal values, but in MX the decimal places are mandatory.
    • Any item labelled unsigned will not accept a minus sign. Those labelled signed don't need + for positive, but do need - for negative.
  3. The third column shows an example of a value accepted by Cumulus 1
    • The file content rules for MX changed in release 3.7.0, and it has not been verified that all Cumulus 1 examples are still accepted
    • For Cumulus 1, where decimals are allowed, the stored value might be an integer as this depends on a number of factors, including your station type.
    • If you are editing the values manually, you should use integers for humidity, wind bearings, and the two solar radiation figures
    • In Cumulus 1 it is optional to use floating point for the others
    • In Cumulus MX add a ".0" if necessary because MX must see decimal places where these are allowed
    • Note that the figure in a field varies depending on the units you select, and your weather station may not have all the sensors needed
    • In Cumulus 1 any fields defined in the version you are using for sensors you do not have will always contain zero.
    • Also, for Cumulus 1 any fields that are not defined at the version when the line was created can:
      • Either be missing (no fields seen after the last field at your version)
      • Or can be null (field separators only are seen after the last field at your version)
    • MX since version 3.7.0 is more fussy, but less consistent, certain fields contain a single space when not used, others contain zero, and others can be left empty
  4. The final column describes the observation often with a link to where there is more information.

Number of fields per line varies by release

The fields that are available in the release you are running are listed in Monthlyfileheader.txt (found in folder level above the data sub-folder).

If you have some early files with fewer fields than the latest files, there are limited possibilities for calculating correct values for those missing fields

Badge v1.png For the legacy Cumulus software, the number of fields in the file increased as the software was developed. The Cumulus author, Steve Loft, did not provide any utility for populating fields missing from earlier versions of his software. A third party did produce a PHP script that could:

  • add Heat Index to lines created prior to 1.7.11
  • add Apparent Temperature (not other fields, see below) to lines created before 1.9.1
  • add Feels Like temperature (not other fields, see below) to lines created before 3.6.0

The fields that cannot be calculated by this script are (set them all to zero when editing file manually):

  • UV Index
  • Solar Radiation
  • Evapotranspiration (spot value and annual cumulative total)
  • Current theoretical max solar radiation
  • Hours of sunshine so far today
  • Current Wind bearing
  • RG-11 rain today
  • Total Rainfall since midnight (this is for 0900/1000 'rollover' users; normally same as rain today for 'midnight rollover' users)

Badge vMx.png As MX has developed, further fields have been added to the file at 3.6.0 and 3.6.12:

  • Feels Like temperature
  • Canadian Humidity Index (Humidex)

The main MX developer, Mark Crossley, has written a Create Missing utility, this is dependent on having a significantly recent MX release, but it can calculate the following derived values (coping with cases where any of these are missing:

Please note the developer does not mention any of this at his utility details explanation so the author of this Wiki update cannot guarantee the above list is correct

You will need to check in MX release announcements for any update, at time of typing this, the developer has written a routine within CumulusMX.exe to calculate Evapotranspiration, but that is not in the CreateMissing.exe Utility.

Before Version 1.7.10:

Field # Rule Example Description
1(A) Day-Month-Year (2 digits each) 22/04/11 Date as 2 figure day [separator] 2 figure month [separator] 2 figure year - the separator is that set in the your locale for short date format (see setup)
2(B) Hour-Minute (2 digits each) 10:25 Current time to nearest minute (no seconds allowed). Separator must be colon in MX, but can also be set to something else in Cumulus 1
3(C) Signed number 8.1 Current temperature
4(D) unsigned integer 96 Current relative humidity
5(E) Signed number 7.5 Current dew point
6(F) unsigned number 13.5 Cumulus moving 'Average' of wind speed measurements over a particular period (this period can be set to what suits you, but defaults to 10 minutes), (See #Cumulus_Wind_Speed_Terminology)
7(G) Unsigned number 20.3 Cumulus Gust wind speed - the highest wind speed over a particular period (this period defaults to 10 minutes), (See #Cumulus_Wind_Speed_Terminology)
8(H) integer 138 Average wind bearing (in degrees)
9(I) unsigned number 7.2 Current rainfall rate
10(J) unsigned number 5.4 Total rainfall today so far (i.e. resets to zero at daily rollover)
11(K) unsigned number 30.10 or 998.2 Current sea level pressure
12(L) unsigned number 215.2 Total rainfall counter (content depends on weather station type), might be rainfall total so far this year. This figure is not intended to be useful in itself, it may vary for no apparent reason. (It is used internally by Cumulus, but only within current meteorological day.)
13(M) signed number 20.3 Inside temperature This is not available as daily or longer period summary.
14(N) unsigned integer 53 Inside humidity This is not available as daily or longer period summary.
15(O) unsigned number 17.6 Cumulus Latest' measured wind speed (may be a gust) (See #Cumulus_Wind_Speed_Terminology). This is not available as daily or longer period summary.
16(P) Signed number 4.8 wind chill (content depends on weather station type and Cumulus station settings)

Added in 1.7.11

Field # Rule Example Description
17(Q) signed number 8.1 Heat index

Added in 1.8.4

Field # Rule Example Description
18(R) unsigned number 0.5 UV Index (only valid if output by weather station)
19(S) unsigned integer 197 Solar Radiation (only valid if solar sensor on weather station)

Added in 1.9.1

Field # Rule Example Description
20(T) unsigned number 0.08 Evapotranspiration (only valid if output by weather station)
21(U) unsigned number 171.88 Annual Evapotranspiration (only valid if ET sensor on weather station)
22(V) Unsigned number 3.4 Apparent temperature
23(W) Unsigned integer 663 Current theoretical max solar radiation (see the FAQ on Solar max)
24(X) Unsigned number 3.1 Hours of sunshine so far today (only valid if solar sensor on weather station)

Added in 1.9.2

Field # Rule Example Description
25(Y) Unsigned integer 158 Current Wind bearing (See average wind bearing in field 8)

For Cumulus MX editing a file created by Cumulus 1, any of the preceding fields that are not present will be defaulted to an empty string, but there will always be 50 fields (unless you are using MX version before 3.6.0, it which case MX cannot read the file.

Added in 1.9.3

For Cumulus MX 3.6.x reading a line created by Cumulus 1, all the remaining fields will be filled with exactly one space, and editing that to an empty string will be rejected. Cumulus MX before version 3.6.0 cannot read a log file with all lines in that log file created by any Cumulus 1 version prior to 1.9.4.

Field # Rule Example Description
26(Z) Unsigned number 6.0 RG-11 rain today (only valid if output by sensor) This is not available as daily or longer period summary.

Added in 1.9.4

Field # Rule Example Description
27(AA) Unsigned number 5.7 Total Rainfall since midnight (this is for 0900/1000 'rollover' users; normally same as rain today for 'midnight rollover' users)

Added in 3.6.0

Field # Rule Example Description
28(AB) signed number (or space) 13.7 Feels Like temperature

NOTE: MX adds a space here, if a line (created before 3.6.0 without a valid value in this field) is edited.

Added in 3.6.12

Version 3.6.12 (build 3088) was an emergency release to cure serious problems in previous build 3087. It added the following field, but until version 3.7.0 (build 3089) the extra field is empty.

Field # Rule Example Description
29(AC) signed number 13.7 Humidex

Added in 3.nn?.0

This new field makes it easier to work out a time in UTC, and identifies uniquely those lines created during a switch from Daylight Saving Time to Winter time, that would otherwise have duplicate times for an hour at time-zone changeover.

The following change was initially planned for release of MX 3.9.0 (b3095), but this section has been amended as the introduction of this new field has been postponed, because of implications of other changes planned at same time (see below table).

The developer has said it is still his plan to add this field during a major release in 2022, but he cannot yet say when it will actually be available to public.

Field # Rule Example Description
30(AD) datetime integer 1579564800000 UNIX time-stamp

The proposed "Updates.txt" entry read

- Major changes to how Cumulus MX handles it's data files
	- Dayfile.txt
		- The date field format is now fixed at "dd-MM-yy" (old order is retained for third party compatibility)
		- The decimal point is now fixed at "."
		- The list separator is now fixed at ","
	- Monthly log files
		- The file names are fixed at "yyyyMMlog.txt"
		- The date field format is now fixed at "dd-MM-yy" (old order is retained for third party compatibility), any lines using "dd/MM/yy" are converted to new separator
		- The time field format is now fixed at "HH:mm"
		- An extra field is added that is the UTC date-time integer
		- The decimal point is now fixed at "."
		- The list separator is now fixed at ","
	- Extra Data log files
		- No change in file names
		- The date field format is now fixed at "dd-MM-yy" (old order is retained for third party compatibility), any lines using "dd/MM/yy" are converted to new separator
		- The time field format is now fixed at "HH:mm"
		- An extra field is added that is the UTC date-time integer
		- The decimal point is now fixed at "."
		- The list separator is now fixed at ","

Accessing the Standard Log File

Please see Calculate Missing Values and Correcting Extremes for full details on relevant functionality in Cumulus software.

Access to current log by other processes

As the log file for the current month will be updated frequently by Cumulus (when it is running), Cumulus 1 applies an exclusive lock, and conflicts can happen if another process seeks to access this file. Consequently don't let your antivirus scans access this file, nor try to edit it outside Cumulus while Cumulus is running. Whilst MX does not apply such locks, it would be unwise to externally edit a file that is being frequently updated while MX is running.

Also note these log files do not include a header line, and should not be edited to include it.

Additional ideas for how any Standard Log File can be used within Cumulus

Uploading current log to your web site

The current standard log can be updated at your usual web site update interval using <currentlogfile> as the local file name. If your web site upload interval is the same as the logging interval, there might be a conflict because of the file locking, so this might not work every time. However, extra web files are not processed all at once, so by listing this file against a higher number the chance of conflict is reduced.

    • For Cumulus 1, list this log file as the local file by specifying the parameter 'ExtraLocal[0-99]=<currentlogfile>' in Cumulus.ini_(Cumulus_1)#Section:_FTP_Site).
    • For Cumulus MX, use the Extra web files option within the "Settings" tab, and enter "<currentlogfile>" in the local column.
  1. You can also use <currentlogfile> as part of the remote file path, as explained in the Cumulus Help. You will also need to specify a path in the remote column for MX or the 'ExtraRemote[0 to 99]=...' for Cumulus 1. You might of course want to specify a local path, and leave the FTP column unticked (or set to 0 for Cumulus 1). You can then use a separate FTP process to upload this copy.
  • It is recommended that you do not try to FTP the actual standard log file (instead FTP a copy) because the FTP process is relatively slow, particularly as the file size increases as the month progresses, so there is an increasing chance of conflict with logging the next line of values - see support forum here for more information.
  • An alternative approach is to upload the standard log file just once a day, at a quiet period such as an odd number of seconds after quarter-past midnight using a process scheduled outside Cumulus.

Cumulus 1: transferring the contents of the standard log file into a database table

  • A script can be used to read the your copy of the standard log file into either a database table (see ImportCumulusFile), or into an array, for further processing.
  • It is, as advised above, best to work with a copy of the file that Cumulus is actually updating, because there can be a conflict of the locks, Cumulus needs to have exclusive use when it does its normal update.
  • But this script can safely be used with older standard log files, or a copy of the latest standard log file.

Cumulus MX: transferring the contents of the standard log file into a database table

Crystal Clear info.png This document is 'Work In Progress' so content may not be complete.

Request for help from Wiki Readers

  • Do you understand how MX works?
  • Do you use hardware, or MX functionality, that is not yet documented? Can you begin that documenting?
  • Can you contribute simple text for novice users, examples of what you have done, correction of typing or factual errors, or supply missing details?
  • Will you make this page more useful by bringing content up-to-date as new releases change some information written for older releases?
  • Does any page need a section for novices, so they don't need to read more technical information further down that page?
  • Is there some information on this page, that should be on a separate page? Can you create the new page and move the less relevant information off this page, don't forget this page needs a link to the new page so people who expect to find it here know where it has moved to?

If you plan on contributing to the Wiki, then you will need an account.

  • Please use the Request Account form to apply for an account. Note that the Wiki is currently undergoing restructuring and is largely locked for editing, but please apply for an account if you wish to contribute in the future.
  • You will find help on how to contribute to this wiki at How to Edit.
  • If you need to consult others, please use the Cumulus Wiki suggestions forum.

Please be aware that information on this page may be incorrect.

PLEASE UPDATE THIS SECTION - ExportMySQL.exe HAS BEEN REPLACED BY ExportToMySQL - see forum for an example

Although the ImportCumulusFile script can be used with MX too, MX provides 2 other ways to transfer the contents of a Standard Log File into a database table.

  1. The first, uploads ALL past data, using ExportMySQL.exe found in the top level folder where CumulusMX.exe is found. It can be run using the same way as you run the main program, but you need to specify "monthly" as the first parameter (this indicates the table name that is to be updated, it does not work for any other table name).
  2. The second, which only uploads the line most recently added to the standard log file is found in the My SQL settings section of the admin interface. Find more information at MySQL settings. In this option the default table name is "monthly", but it can be changed.

Additional Functionality in Cumulus

  • Additional derived values in original Cumulus software
    • You can see Mean temperatures, Air frosts, Gale days, Rain days, Dry days, and Total Wind run using View menu displays for This month, This period, and This year (These figures are not stored anywhere, nor available as web tags), but Cumulus 1 can calculate these from what it finds in the standard log files and the daily summary log.
    • You can use create missing button in the dayfile.txt selection in the Edit menu.
    • create the relevant monthly and/or annual NOAA style report by choosing NOAA Monthly Report or NOAA Annual Report.
      • In Cumulus 1 do this from the View menu, then select the required period using the selectors. Click the Update Display button to see various statistics (including mean temperature) calculated. Generation of complete NOAA reports takes most information from dayfile.txt (based on rollover to rollover meteorological days), except average wind speed and dominant wind direction (both of these it calculates from values read from the standard log files) for period in question. Finally press Save button to store the new or amended report.
  • The last of these is also in MX
    • In Cumulus MX, use the Reports tab, then choosing NOAA Monthly Report or NOAA Annual Report. A date selector allows you to choose the exact report you want, click "Load" button next to it. You can alternatively click another button to generate a missing report, or to regenerate an existing report after any corrections you have made to any standard log file relevant to that report.

Rules to follow if editing a standard data log

Important Rules for Cumulus 1

  • Each line must contain the fields in correct sequence (since new versions/builds can add to number of fields, Cumulus will accept different months having various row lengths i.e. older ones without the more recent fields at the end).
  • The date format uses two digits for the year and should be treated as text. For software (e.g. Excel) with default of recognising formats, ensure that such recognition is turned off, as it is likely to change the dates to either a number representing days since e.g. 31 Dec 1899, or to have four figure years, and then Cumulus will no longer be able to use the log file. (Also the month must be the middle figure, USA convention cannot apply within Log_Files).
  • Times in these files are in the form hh:mm using the 24 hour clock and local time (system time). See FAQ#How_does_Cumulus_handle_Daylight_Saving_Time.3F.
  • See #List_of_fields_in_the_file to identify if the value you enter for a particular field is an integer (like bearings and humidity values) or a real number (like pressure and rainfall values) in format x.y using your system decimal notation for the decimal point. Fields that accept real number format will also accept integers, but fields expecting integers will not accept decimal points.
  • Negative values are allowed for temperatures, all others must be zero or positive. Humidity has a maximum of 99, bearing has a maximum of 360.
  • Nulls (',,' if your field separator is a comma, ';;' if your field separator is a semicolon) are not allowed in the row, so if you do not know the value for a particular field within the row, then type in a zero, -999, or 9999 (check the format in the middle column of #List_of_fields_in_the_file and think about the range of numbers allowed for particular fields as per examples in previous bullet). In other words put in an obviously strange number as Cumulus does not have a defined null! This strange number may distort graphs and any calculations, but it will remind you to make a more appropriate guess as soon as you can.
  • Note that some fields (e.g. those related to evaporation, UV, solar data) will only contain valid data if your station has the appropriate sensor(s) (without the sensor they contain the default value of zero), but if they apply make sure you note which are stored as integers.

Equivalent rules for MX

  • All fields in all lines must contain the same character for separating one field from next and it must be consistent with whatever locale you use when you run MX (it might be set using a parameter to the command running MX, it might be set in Mono, or in Windows control panel).
  • Each line must contain all the fields defined in the version of MX that you are using in correct sequence
  • Feels like was added onto the end of this log file in version 3.5.4. Any line in any log file produced before you started using MX version 3.5.4 or later will end with Rain since midnight. However, the way that MX was modified for version 3.5.4 means that those earlier lines will be modified by the application process interface used to transfer log lines between the MX engine and the admin interface to include the full number of fields per row and to contain a space character for that additional field. Consequently, any external edit also has to add a field separator and a space to every line where the original lacked feel like.
  • The date format uses two digits for the year and should be treated as text. For software (e.g. Excel) with default of recognising formats, ensure that such recognition is turned off, as it is likely to change the dates to either a number representing days since e.g. 31 Dec 1899, or to have four figure years, and then Cumulus will no longer be able to use the log file. (Also the month must be the middle figure, USA convention cannot apply within Log_Files).
  • Times in these files are in the form hh:mm using a colon as separator, the 24 hour clock and local time (system time).
  • If you are editing a log file that was produced by Cumulus 1 and it used a separator other than a colon (:) then the old separator must be replaced by colon.
  • For MX the rules for fields containing values are different to those for Cumulus 1, which makes it difficult to successfully edit any pre MX log files. For MX if a field can take a decimal place, it must contain a decimal figure, and it must use the correct decimal separator as defined in locale. If the field only takes integers (see #List_of_fields_in_the_file) then you cannot edit in any decimal places.

Importing pre-Cumulus data

If you were recording weather data manually, or with different weather station software, you might create files, using the standard data log files format, holding that pre-Cumulus data. Cumulus can treat these files just like any where it created the data log entries, and therefore you can apply any of the techniques explained in Calculate Missing Values and Correcting Extremes.

In the configuration file, Cumulus.ini, there is a parameter StartDate=, this is assigned a value when you first start using Cumulus of the current date, in the format specified by the local you are using.

  • The original Cumulus 1 software takes no notice of this date, other than to use it to populate the <#recordsbegandate> see Webtags#Records, so it is quite happy to process standard data logs with lines with earlier dates.
  • The ExportMySQL.exe which was written by Steve Loft and included with the beta releases of MX, and subsequent early MX release distributions from Mark Crossley, also ignores the date in the configuration file.
  • All releases containing CumulusMX.exe, will ignore any data log lines dated before the date in the configuration file.
  • The other Mark Crossley utility packages linked from Software page utilities section will also generally ignore any data log lines dated before the date in the configuration file.
    • CreateMissing.exe will use the earliest date in dayfile.txt if that is earlier than the date in the configuration file.
    • ExportToMySQL.exe (not currently documented in this Wiki) will normally ignore any data log lines dated before the date in the configuration file.

Don't worry if you are using MX and your pre-cumulus data does not have all the fields listed at #List_of_fields_in_the_file. CreateMissing.exe can be used to calculate (at lease some of, maybe all of) those missing fields. That utility will also create dayfile.txt entries for the days in the pre-Cumulus data.

If you are not using MX, you may still be able to populate missing fields (see calculate missing values page), and create lines in dayfile.txt (see Amending dayfile page).

Potential issues when trying to match formats

Here are some issues to consider. There are some postings in the Support Forum about importing past data. Essentially match the fields listed in List of fields in the file below with the fields you have available in your source.

  • Dates and times might need some pre-processing (spreadsheet packages usually have ability to select part of a text string and to concatenate a number of strings) to convert them to text in the formats mentioned above. (Note - it is crucial in a spreadsheet to treat the date as text; Do not let the spreadsheet recognise it as a date as it might change the format or store as a 'days since X' number).
  • Remember that null values are not allowed within a row, so ensure that you enter an obviously wrong value (-99 or zero might be do) between your operating system defined field separator (normally ',' or ';') and make the row length the minimum shown in the list of fields below. If you use a spreadsheet, treat the file as Comma Separated Value type, but on saving choose the appropriate field separator character (e.g in Libre Office or Open Office 'Save as CSV' select 'Edit Filter Settings').
  • Wind directions might be reported as cardinal points (north, south etc) and need converting to bearings in (integer) degrees (spreadsheet packages provide look up functionality to do such conversions).
  • Wind speed fields may not directly match to weather station outputs. See #Cumulus_Wind_Speed_Terminology
  • Temperature fields may not directly match to weather station outputs. Copy across the fields you can and set the others to -999.99 so they are obvious. See the workaround described below for a way of getting Cumulus to generate (from your newly created monthly logs) apparent temperature, wind chill and heat index to replace any -999.99 figures.
  • Rainfall fields may not directly match to weather station outputs. Rain rate in field 8 may be generated by following advice in Calculate Missing Values.

Cumulus Wind Speed Terminology

This section was written for the original Cumulus software. There are some differences in how MX reads information from weather stations, particularly those by Davis, but that should not affect content below.

How wind speeds relate to various weather stations is explained in FAQ. Basically there are 3 values processed by Cumulus:

  1. Gust - the highest wind speed over a particular period (this period defaults to 10 minutes),
  2. Average - the moving average of wind speed measurements over a particular period (this period can be set to what suits you, but defaults to 10 minutes),
  3. Latest - the most recent (wind speed or gust speed) measurement.

FAQ: Wind speeds in Cumulus with Davis stations, the EasyWeather differences in FAQ: Wind speeds in Cumulus with Fine Offset stations and FAQ: Wind speeds with Oregon Scientific and La Crosse stations

When Cumulus is running normally, it actually stores (in the fifth item after the date in each entry, column F in a spreadsheet) the highest (moving) average in the period since the previous logger record (assuming you have a) kept default averaging interval to 10 minutes, and b) have also adjusted the logging interval from the default 15 minutes to be 10 minutes).

If Cumulus is not running, it stores the average from the station logger, that is the latest reported moving average. For this reason the most accurate wind speed records are achieved if Cumulus is running all day every day.

Cumulus calculates the monthly/annual/period average wind speed (as used for 'This ...' screens in View menu and the NOAA report) by trawling through the relevant standard logs, summing the values for those individually logged average wind speed, and dividing by the number of entries for the required calendar days. It therefore assumes that each entry has equal 'weight', i.e. each one covers the same period. If your standard log(s) is/are a mixture of values stored while Cumulus is running and values copied from the station logger during periods when Cumulus was not running, then it is possible the two logging intervals have not been set to the same time, so the output value could be skewed for that month/year/period because of the difference in what was stored and the difference in the logging interval.

Windrun is also calculated from average wind speed measurements, in this case every minute if Cumulus is running, or from the values that are logged (at station logging interval) as average wind speed when Cumulus is restarted and catches up from the station logger. Again, if Cumulus is not left running the calculated value will be skewed.

Example lines from the file

Note that your field delimiters may be different, and your date delimiter too.

An extract of a few lines of the file (v.1.9.0)

Here logging is quarter hourly, the field delimiter is a semicolon, the decimal separator is a comma, and the date separator a dash.


this is an example of a file from 1.9.1, with solar data:

Here logging is increased to every five minutes, the field delimiter is a comma, the decimal separator is a full stop, and the date separator is also a full stop.


and from version 1.9.2:

Here logging is at the default interval (10 minutes), and the delimiters have their default settings for UK systems.


and from version 3.6.0:

Here logging is at the default interval, and the delimiters have their default settings for UK systems.