Dayfile.txt

This Wiki page applies to both Cumulus flavours.

As part of a redevelopment of Wiki, this page has been simplified, by moving some content to new pages. Old links in the support forum, that were to content no longer on this page, will bring you here.

Content previously on this page has been moved as follows:

• Explanations about Cumulus terminology can be accessed from Category:Terminology page
• Each line in this file represents one day, but the start time need not be same for all fields,
  • so please see Meteorological day, and today.ini for more details about that
• Advice regarding editing this file has been moved to Amending dayfile page, this also covers date-separator issues and dealing with missing or corrupted lines
• General advice about Cumulus files with a .txt extension has been consolidated on Category:Files_with_Comma_Separated_Values page
• Advice about correcting any rogue extreme figures inadvertently stored in this file has been consolidated in new Correcting Extremes page
• If some lines in your file have fewer fields than other lines the advice has been consolidated on Calculate Missing Values page
  • For MX there is a Create Missing Utility, which checks spot readings in the MMMyylog.txt files, adds any missing derivative spots (e.g. heat index) and uses these figures to recalculate daily derivatives and uses those to replace missing fields/lines in dayfile.txt
  • For the legacy Cumulus, there was a dayfile editor with create missing option, that performed equivalent function
  • If you import historic data from before you started using Cumulus into Standard log files,
  • then see Calculate Missing Values page for how to generate new lines in dayfile.txt
• Cumulus MX is more fussy, than Cumulus 1, about various formatting issues, see below, also see Migrating_from_Cumulus_1_to_MX#dayfile.txt section for more advice

The content that remains on this page is summarised by the table of contents that follows.

About this file

• This Wiki page describes one of the files not included in any release download.
• This daily summary file (Steve Loft shortened that to "day" plus "file") uses a ".txt" extension, and is essentially a plain text file in CSV format.
  • CSV stands for "Comma Separated Values", but in the Cumulus context the field separator can be other characters including ";" or "|"
• The file is created in data sub-folder of your Cumulus installation when Cumulus needs to store its first line in this file.
• Cumulus MX reads the whole of this file into an internal array (stored in RAM) each time you restart the software,
  • Please see here for implications
  • Therefore MX users who move to a different location should archive the old "dayfile.txt", to avoid any discontinuities in any graphs plotted from active file

(speciallog.txt is another log file that contains all dates in a single file, as do all the .ini files).

How Cumulus Creates and Updates this file

• Cumulus reads values supplied by your weather station, (either directly while Cumulus running, or for some weather station types can read historic data during catch-up on restarting Cumulus)
• Cumulus converts them to the units you prefer,
• Cumulus applies any calibration (multiplier and offset) you have set,
• For a sub-set of those readings (perhaps those every minute if readings are collected every 10 seconds), the spot values of source items like temperature, humidity, wind speed, can be used in calculations of derived items like "wind chill", "dewpoint" and "feel-like" temperature.
• Cumulus then sees if the resulting soource, or derived, value implies any extreme records file needs to be updated
  • Daily extremes are held in today.ini and that is main source used when a new line is added to "dayfile.txt"

Why this file should be backed up

• This file contains daily extremes, the accuracy of those daily extremes depends on the interval between the spot readings that are used as explained above.
• If the file is corrupted, and not regenerated from a back-up, the only source of spot readings is the MMMyylog.txt files, and their interval might be only every half an hour (it has to be an exact fraction of an hour).
• As explained here minima and maxima between such logging intervals are not recorded by Cumulus software
• Thus it is worth backing up this file, to another device than that running Cumulus, on a regular basis, probably a few times a week, to ensure this precious data is not lost if your device running Cumulus has a malfunction (or is damaged), or an electrical blip (or mistake by you) causes corruption to the original file,

Cumulus does periodically copy this file within the installation, but the copies are only kept for a limited time, and are on the same physical storage device, and so your main file is corrupted you might not be able to access the Cumulus back up or might not be able to go far back enough to find a file that has not been corrupted:

• The file is backed up when MX is restarted into a date/time stamped sub-folder of the backup folder
• The file is also backed up (to a date/time stamped sub-folder within daily sub-folder of that backup sub-folder) during the end of day process, but (depending on the release you are running) the back-up copy may, or may not, include a line for the previous day (the line that is appended in the same end of day)

Retention of these back ups:

• MX only keeps the last 9 of the date/time stamped sub-folders.
• Legacy Cumulus 1 only keeps up to 8 of the date/time stamped sub-folders.

Specific issues for MX

WARNING: It is important to note that some releases of MX are very fussy about consistency in all lines of dayfile.txt. Earlier releases tended to have better compatibility with the legacy software. Subsequent releases expected every line to be expressed exactly as specified in the locale. MX in its latest release is trying to cope better with inconsistent date separators.

Date field: Cumulus 1 (C1) did not care what character (or characters) separated the day, month, and year elements of the date field. MX insists that the same character (or characters), as defined in the locale, is used for all lines in file.

Real number fields: MX uses the locale to decide what character (decimal comma or decimal point) separates integer and decimal parts of numbers. Every line of the file must be consistent in use of integer/decimal separator. C1 used the Region settings in Microsoft's Control Panel to determine how to store (and output) numbers for you, but (except if list separation character was comma) was fairly tolerant when reading old data in files. At the time of writing this, it was proposed the next major release will force this file to use decimal points (full stops not commas) regardless of locale. This proposal may or may not happen, the point is that information here might be incorrect for the release that you are using.

Time-stamp fields: MX insists on HH:mm format being consistently used in every line of file, C1 did not care what (non-space, non-field separator) symbol separated the minutes from the hours.

Number of fields: The number of fields in the file increases in various versions as shown in #List_of_fields.

• C1 will accept (as did Cumulus 2) any line with 15 to 45 fields in it. This is because the earliest version only stored 15 fields, as C1 was developed fields were added (as shown in field list) until there were 45 fields.
• Each release of MX expects a particular number of fields in each line of file; MX has added fields as the software has developed, and it even (as shown in field list) inadvertently added 2 fields later removed. The difference is that MX (for some functionality from release 3.4.5, for all functionality from release 3.9.5) reads the whole file into an internal (RAM held) array with a fixed number of elements, therefore every line ends up with same number of fields when written back into file.
  • If you have some lines in your file that were created by an earlier release of Cumulus, and so have less than whatever is the current number of fields for the release you are using, there is a utility to run that will create a new dayfile.txt with all fields populated, please see Calculate Missing Values page. Please ensure you use the right version of the "Create Missing" utility mentioned on that page as it also get upgraded when fields are added, and it uses various software libraries contained within .dll files specific to a particular CumulusMX.exe release.

How to view or edit this file

The detailed information has been moved to viewing/editing dayfile.txt page.

An editor has been included within recent Cumulus releases of each flavour:

• Available from release 3.4.5 (13 Mar 2020): In the interface go to Data logs menu and select Dayfile
• Available from version 1.9.2 (5th October 2011) to final legacy release: On Main Screen from Edit menu select Dayfile.txt
  • Note for obsolete version 1.9.0 to 1.9.3: There is a bug in these versions in that 'Create missing' inserts 'heating and cooling degree day' values the wrong way round.
  • Note for obsolete version 1.9.3 only: Create missing might in some cases be affected by a bug in 1.9.3 that can cause lines to be stored in incorrect date order (dayfile.txt uses dd.mm.yy, dd/mm/yy or dd-mm-yy, for its date field; and all lines should be in ascending chronological order)
  • There are no known bugs for dayfile.txt handling in version 1.9.4 builds 1086 to 1101. Build 1099 is the standard stable final release of Cumulus 1 for most weather station types, 1100 and 1101 are for specific weather station types.

Please note that the editor in Cumulus 1 allows you to change the date, as well as all the other fields, although the lines must be kept in ascending date order to avoid errors when subsequently reading the file.

The MX editor does not let you change the date, you can only change other fields or delete an entire line, so you have no control over the order of the lines in the file.

Reading the file

See Daily Summary page for a full discussion of ways, external to Cumulus, to read this file.

Apart from the viewing/editing options just described, Cumulus software reads this daily summary file in vaCumulus 1 does not actually number lines, however it does count lines as it reads them, so if there is an error when it reads the file, the original Cumulus will report the line number (numbering from 1) where it first found an error (line numbering uniquely identifies the line, even if a date is duplicated, or a line feed has been deleted so two lines are merged).rious other circumstances depending on the release you are running.

• The legacy software only reads the file when the Cumulus user makes a specific request, in normal operation the existing content is ignored:
  • The legacy Cumulus has a number of screens for viewing data for various periods, to populate these screens Cumulus has to read all of the Files with Comma Separated Values as the derivatives shown generally do not match the extremes tracked in .Ini files.
  • The Select a graph feature also uses all of the Files with Comma Separated Values.
  • The end of day action uses a simple "append" instruction, so it does not need to read the file
• As already mentioned, MX reads the entire dayfile.txt file when it is first started into an internally held array. That internal copy was introduced in release 3.9.2 - b3097 (7 Dec 2020), it was needed to drive the historic charts functionality; both in the interface, and the example included Historic Charts web page.
  • From release 3.20.0 - b3200 (21 Aug 2022) there is a This Period Highs and Lows web page (accessed from Records menu) which is similar to the screens for viewing data for various periods except that the extremes it shows match those tracked in .Ini files.
  • From release 3.20.0 - b3200 (21 Aug 2022) there is an option to Reload dayfile in a Utils menu, this updates the internal held array by reading the file again; essential if an edit has been made to the file.

Line numbering and Error messages

Cumulus 1 does not actually number lines, however it does count lines as it reads them, so if there is an error when it reads the file, the original Cumulus will report the line number (numbering from 1) where it first found an error.

Cumulus MX stores the contents of the file in an internal two dimensional array. The outer dimension is identified by numbering (from zero) what were lines in the file. The inner dimension has that line number as element zero, and the fields taken from file are therefore numbered from one.

Obviously, line numbering uniquely identifies the line, even if a date is duplicated, or a line feed has been deleted so two lines are merged in the file. This is why you will see line numbers quoted in any error messages related to this file.

Some of the editors you may use to view/edit the file may number the lines (in some cases always, in others as an option). If you have seen an error message, then to correct the file you need to use a tool that does number the lines in order to find where the correction is needed. Error messages report just the first error found, so check subsequent lines in case they have same error.

List of fields in dayfile.txt

For your installed build please see dayfileheader.txt. This file identifies all the fields in each line of the dayfile.txt file in the release you are running.

That file has changed location from release 3.20.0 - b3200 (21 Aug 2022), it is now in data folder, for Cumulus 1 and all earlier MX releases it was in same directory as the Cumulus executable.

As explained earlier, the number of fields in a line has (with one exception when fields were added in error) increased as the Cumulus software has been developed. The table below therefore groups the fields under labels that indicate which version/release introduced them.

Field numbering

The table below was first created when the only flavour of Cumulus software available was what we now call the legacy Cumulus 1. Back then the fields were numbered starting from zero. This reflected the way fields were identified when processed as elements of an single-dimension array variable representing a line.

The old numbering from zero had two advantages:

1. It stressed that the date field was different to the rest, all other fields were either values or time-stamps
2. Numbering starting from zero is consistent with standard indexing used for arrays in programming languages (like JavaScript), so the number shown was the number to quote in any scripts where a Cumulus 1 line was converted to an array, and you needed to address a single field.

Please note the list of fields has been rewritten especially for MX. As part of the rewrite, the fields have been renumbered, in some forum posts you might see references to old numbering, in others to new numbering. As explained above the fields are now numbered starting from 1 to fit in with an internal array created when the log file is read, the processing code adds a line number in front of the date field on each array 'line' it holds.

Information shown in the table

• The date is supposed to be a unique identifier, the same date should not be repeated in another line, however Cumulus 1's editor allows you to change that date field.
  • The dates, as mentioned earlier, should be in ascending order.
  • Please see amending dayfile page for more information on dates
  • Both Cumulus 1 and MX may get confused if you restart the software close to rollover time, and in that confused state they may create a second line with same date as a date already in the file.
  • If you regularly restart Cumulus close to rollover time, then a whole sequence of dates can be repeated either as a block or as pairs.
• The remaining fields are all either numerical values, or a time paired with (except for first wind field) preceding numerical value.
  • Cumulus 1 actually enforces this pairing (i.e. it validates that a time is present where it is needed). Cumulus MX only validates that each field is of correct type, it does not recognise any relationships between fields.
• The alphabetic column identifiers used by many spreadsheet editors are shown in the table
  • IMPORTANT: If you do use a spreadsheet editor, do ensure all columns are set to "text" format,
  • Note that you will corrupt this file if you let your spreadsheet recognise content as dates or time, or let it change the number of decimal places.
• The type of field is shown in the table:
  • Note you must not include a sign for an unsigned field,
  • Note you can not specify a decimal comma/point in an integer field,
  • Note all fields of type time must use 5 character "HH:mm" format, although Cumulus 1 will accept other separator characters where ":" shown.
• The field description is shown, together with references to where that terminology is explained

Table listing Fields

Field number	Spreadsheet column	Field type	Description
0	For internal MX purposes, the zero field identifies a field that holds the line number. It is not actually stored as a field in the log file, but precedes any line exchanged via an application programming interface, and therefore is also included in an array representing all the fields in any log file line. If you are processing this log file using a third party (or your own) script, that probably does not place the line number into any array, and your array elements will start at 0 for the field labelled 1 in this table, so putting all field numbers out by 1.
Those fields included below have been in dayfile.txt from the start of Cumulus 1 (Version 1.0, the First release on 27th January 2004).
1	A	8 characters	Date as 2 figure day [separator] 2 figure month [separator] 2 figure year - the separator is that set in the windows system short date format (see setup)
2	B	Unsigned number	Highest wind gust speed
3	C	unsigned integer	Bearing of highest wind gust
4	D	5 characters	Time of highest wind gust
5	E	signed decimal	Minimum temperature
6	F	5 characters	Time of minimum temperature
7	G	signed decimal	Maximum temperature
Consistency Note: In some cases Minimum comes before Maximum, in other cases Maximum is before Mimum
8	H	5 characters	Time of maximum temperature
9	I	Unsigned number	Minimum sea level pressure
10	J	5 characters	Time of minimum pressure
11	K	Unsigned number	Maximum sea level pressure
12	L	5 characters	Time of maximum pressure
13	M	unsigned number	Maximum rainfall rate
14	N	5 characters	Time of maximum rainfall rate
15	O	unsigned number	Total rainfall for the day
Above here represents the minimum length for every line, a count of 15 items
[There is no record of which version added this next field. The Cumulus Support Forum, while it was hosted by Steve Loft, moved to new forum software (phpBBB3) on 2 Jun 2008, and started afresh without retaining any previous content. Therefore all announcements about the content of each build prior to version 1.7.9 were lost. All that can be deduced is that it was between versions 1.2.5 and 1.5.1 as these do not appear in the release history issued by Steve Loft. The first mention of it in the new forum was not until December 2008, but that was not about when it was released. A web tag for this variable was added in Build 978 of 1.9.1 beta, which was obviously long after it was first calculated. Because of that, in "DataEditor.cs" (part of the source code that is compiled into CumulusMX.exe) this addition has "Extended for ???" as a comment]
16	P	signed decimal	Average temperature for the day
(Wind run was added from version 1.8.4)
17	Q	unsigned number	Daily wind run
(The next pair of entries were added from version 1.8.9 build 907 (June 2010) as part of a total redesign of how dayfile.txt was implemented in Cumulus 1)
18	R	unsigned number	Highest Average Wind Speed
19	S	5 characters	Time of Highest Avg. Wind speed
(The two pairs of humidity entries were added in October 2010, a v 1.9.0 beta, the exact build number is now lost)
20	T	unsigned integer	Lowest humidity
21	U	5 characters	Time of lowest humidity
22	V	unsigned integer	Highest humidity
23	W	5 characters	Time of highest humidity
(The next two entries were added from version 1.9.0)
24	X	(not documented)	Total evapotranspiration (Only valid for Davis stations, shows zero otherwise)
25	Y	unsigned	Total hours of sunshine (only valid if sunshine sensor connected) Important if rollover time is 9 am or 10 am: Most fields in this file are updated taking information from today.ini. For a non-midnight rollover, then the Sunshine hours reported here is from 00:01 on the calendar date corresponding to the date in the first field of this file, to subsequent midnight, and that end time is 9 or 10 hours before when this file is updated. Meanwhile, the sunshine hours count has been reset and so the figure in today.ini is not what is wanted here. For that reason the sunshine hours reported here are taken from yesterday.ini.
(The next 16 entries were added from version 1.9.1 May 2011)
26	Z	signed decimal	High Heat index (added to Cumulus in 1.7.11 only as spot value, not stored)
27	AA	5 characters	Time of high heat index
28	AB	Signed decimal	High Apparent temperature
29	AC	5 characters	Time of high apparent temperature
30	AD	signed decimal	Low apparent temperature
31	AE	5 characters	Time of low apparent temperature
32	AF	unsigned number	High hourly rain
33	AG	5 characters	Time of high hourly rain
34	AH)	signed decimal	Greatest wind chill (high wind speed, low temperature) (calculated since version 1.8.3 as spot value, not stored)
35	AI	5 characters	Time of greatest wind chill
(The next two pairs for dew point were added in version 1.9.2 beta build)
36	AJ	signed decimal	High dew point
37	AK	5 characters	Time of high dew point
38	AL	signed decimal	Low dew point
39	AM)	5 characters	Time of low dew point
(The next three entries were added in version 1.9.2 Build 1004)
40	AN	unsigned integer	Today's dominant/average wind direction
41	AO	unsigned decimal	Heating degree days
42	AP	unsigned decimal	Cooling degree days
The next two pairs were added in legacy version 1.9.3 build 1036 (these only show valid values if appropriate sensors exist). Fields listed up to those following here applied to the final legacy Cumulus 1.9.4 and formed the basis for early releases of Cumulus MX.
43	AQ	unsigned decimal	High solar radiation
44	AR	5 characters	Time of high solar radiation
45	AS	unsigned decimal	High UV Index
46	AT	5 characters	Time of high UV Index
The next two pairs were added in MX release 3.6.0, 2 more derived values and their times
47	AU	signed decimal	High Feels Like temperature
48	AV	5 characters	Time of high feels like temperature
49	AW	signed decimal	Low Feels Like temperature
50	AX	5 characters	Time of low feels like temperature
The next two pairs were added in release 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 4 fields (2 values and their times). The 4 extra fields are left empty in this release, although you can add values and time-stamps using the dayfile editor. From release 3.7.0 the first 2 of these 4 fields are populated, and the last 2 are removed, so I have labelled them as error.
51	AY	signed decimal	High Canadian Humidity Index or Humidex
52	AZ	5 characters	Time of high Humidex Bug for releases 3.13.0 to 3.14.2 inclusive: The major code rewrite for release 3.13.0 replaced the previous code for the processing for all Cumulus files, the new code incorrectly stored Time of high feels like temperature in this field for all these releases! Corrected in minor code rewrite for 3.14.3 - b3163 25 Jan 2022 (not released to public until 3.15.0 - b3169 Released 31 Jan 2022)
Just confirming that the next 2 fields were included by mistake in an emergency release (3.6.12), and are not included in any other version, so have labelled them as error.
53 (error)	BA	signed decimal	Labelled as Low Humidex, but not used, (appear in 3.6.12, but no other release)
54 (error)	BB	5 characters	Labelled as Time of low Humidex, but not used, (appear in 3.6.12, but no other release)
The next value was added in release 3.12.0
53 (new)	BA	unsigned decimal	Cumulative Chill Hours since start of season
The next value and time fields were added in release 3.20.0
54	BB	unsigned decimal	Highest rainfall total in (an approximate, as it depends upon timing of earlier entries in Recent history) 24 hour period ending in Meteorological day
55	BC	5 characters	Time when (approximate) 24 hour period for rainfall total above ends

Example of the file

An extract of a few lines of a dayfile.txt

01/08/11,19.3,61,10:22,12.5,06:58,23.8,14:49,1014.26,20:46,1018.83,09:28,0.0,00:00,0.0,17.8,21.6,4.6,10:44,36,14:14,86,01:56,3.56,8.9,23.8,14:49,23.1,14:50,12.3,06:59,0.0,00:00,12.5,06:58,11.3,00:16,6.9,14:34,354,2.0,1.5

02/08/11,16.1,20,16:55,14.7,06:45,24.2,13:54,1013.79,19:13,1015.65,11:14,0.0,00:00,0.0,18.9,13.7,8.0,15:55,42,20:42,85,06:50,2.79,4.9,24.2,13:54,24.3,13:55,15.1,06:40,0.0,00:00,14.7,06:45,14.8,11:59,7.0,21:09,57,1.0,1.7

03/08/11,14.5,36,17:23,14.9,05:50,24.6,14:46,1012.70,18:44,1015.99,08:34,0.0,00:00,0.0,19.4,17.2,4.8,16:04,50,14:38,79,07:04,3.05,5.8,24.6,14:46,25.4,14:47,15.0,05:50,0.0,00:00,14.9,05:50,14.2,20:01,8.9,00:16,32,0.8,1.9

04/08/11,17.7,16,15:43,14.1,06:20,25.3,15:06,1013.08,18:42,1015.31,08:28,0.0,00:00,0.0,20.2,19.4,8.1,14:12,52,18:20,92,06:55,3.30,9.1,25.3,15:06,26.8,14:55,14.9,06:20,0.0,00:00,14.1,06:20,15.8,14:55,12.5,06:25,36,1.0,2.9

05/08/11,16.1,32,12:52,14.2,06:12,22.2,14:07,1013.89,00:01,1016.36,09:43,0.0,00:00,0.0,18.6,21.6,5.2,13:00,62,15:57,87,06:11,3.30,8.4,22.2,14:07,23.5,14:10,14.8,07:19,0.0,00:00,14.2,06:12,15.4,10:33,12.0,06:03,34,0.9,1.3

06/08/11,16.1,309,11:15,14.3,05:29,22.4,17:12,1014.46,20:02,1016.97,10:38,0.0,00:00,0.0,18.4,19.2,5.5,16:21,55,13:33,92,05:20,2.79,7.9,22.4,17:12,23.3,18:17,15.1,06:09,0.0,00:00,14.3,05:29,14.2,18:12,10.9,10:38,32,1.1,1.3

07/08/11,17.7,342,13:24,12.9,05:47,24.1,14:53,1013.92,19:49,1016.43,09:36,0.0,00:00,0.0,18.4,19.1,6.3,14:06,48,12:45,89,05:36,3.30,9.0,24.1,14:53,24.6,15:48,13.3,05:47,0.0,00:00,12.9,05:47,14.6,15:52,10.7,11:33,11,1.6,1.7