Dayfile.txt

From Cumulus Wiki

Introduction

Cumulus maintains a daily log file that holds the highs and lows of each day, as well as a few other nuggets of information. In all flavours of Cumulus, this file is only updated (with exclusive lock) during the end of meteorological day process. In that process it is also read if the generation of NOAA reports has been requested.

In Cumulus 1 only, the figures contained in the file are used for the 'This period' display accessed from the View menu and to build any graphs based on daily values.

The format of this file is the same for both Cumulus 1 and Cumulus MX, although the number of fields in the file increases in various versions as shown at the end of this article. The file can be ported between flavours only if both are run with exactly the same locale settings, as using a different locale may change the field separator or the symbol used for decimal points.


Changes in different releases of Cumulus

Cumulus Version 1 Specific

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 incorrect date order for records (dayfile.txt uses dd/mm/yy or dd-mm-yy and all records should be in ascending chronological order)

There are no known bugs for dayfile.txt handling in version 1.9.4 builds 1086 to 1100. Build 1099 is the standard final release of Cumulus 1 as this section was updated.

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Cumulus MX v3.0.0 (checked at build 3043) does not provide an editor

Cumulus MX Version 3.4.5 - Build 3069 onwards provides an editor

When Cumulus is left running

  • Cumulus is frequently reading observations from your weather station, but these don't affect the daily log "dayfile.txt" as it is only updated once a day.
  • There are no updates to dayfile.txt at any other times, but (for Cumulus 1 only) the contents of the file are read and processed for many of the display and edit menu options that can be selected from the main Cumulus 1 screen.
  • Cumulus tracks the highs and lows in weather observations by comparing read values against those it has stored in Today.ini, updating that file as required. (It also updates Alltime.ini, Monthlyalltime.ini, Year.ini, and Month.ini when appropriate.
  • Cumulus will not mind you accessing the daily log outside its software, except when it needs write access for processing end of day.
  • If you do need to correct some rogue data in the log file, first take a copy and work on that copy, because any edits you do could muck up the specific format that Cumulus 1 or MX needs, there is a section on dealing with rogue data below. Only when you are absolutely sure that your edited copy meets all the constraints listed later, should you replace the original.

When Cumulus processes the end of the (meteorological) day

  • A new row is appended to dayfile.txt, the values are prepared from reading "today.ini" file, not all values available in "today.ini" are stored in dayfile.txt.
  • Some of this information is also stored in yesterday.ini.
  • Back ups of both today.ini, and dayfile.txt, log files in their state after the end of day update are copied to the 'cumulus\backup\daily' folder, a maximum of only 9 daily sub-folders are retained.

Optional

  • Some people require a copy of the local file to use on their web server. Consequently, after it has been updated they file transfer it to (or if their web server is local, copy it to) their web server. One way of doing this is described here.
  • Some people take a copy of the local file, and use it locally for other purposes. See How you can use the daily log section and also the [[Cumulusutils]] link.
  • For some people it is easier to follow an option of converting the file into a database table, and that table having a new row added each time the file gains a new line as described below.

Populating a database table

  • The article here describes a method that can be used with Cumulus 1 to mimic the contents of dayfile.txt in a database table. However, be aware that the later versions of that script have bee edited for MX, so you will need to use an older version of the script that fits the version of Cumulus 1 you are using.
  • There is a section at Cumulus MX to explain how MX includes the ability to generate SQL for creating the database table, for updating it with past data, and to add a new row at the end of the day for the standard database table version of this daily summary log.

Using that table

In both cases, your web site can use that database table avoiding any clash of timing with the Cumulus 1 or MX use of the daily summary log.

For examples of some of the third party tools (Cumulus) using the database daily summary table see here. Of course there are also a lot of tools written to use a copy of the dayfile.txt log file, and some of these could be adapted to use the database table instead, if you are a programmer.

In my case I also store the equivalent of what appears on my version of "thismonth.htm" each month in another database table, i.e. I have one database table column for each of the weather derivatives I show on my web page that show this month's values; it is many more derivatives than are shown on the standard web page, but some are initially hidden. Consequentially, when my daily update script detects from the date that it is processing the last day of a month, it then starts another script that reads all the rows in the daily summary table for that month, and stores the highest/lowest/total (as relevant) in my monthly_summary table (nothing to do with the "monthly" table that MX can generate). This monthly summary table allows me to have web pages that compare consecutive months or compare months between years. Just another example of how much you can get from just one log file!


Alternative schemas

Of course you do not need to exactly mimic the log file with the schema in your database table, your weather station may not produce solar values so those fields in dayfile.txt need not be columns in your database table, or you may wish to add other values from external sensors or other log files.

Cumulus Version 1 Specific With Cumulus 1, you would need to be a programmer and write your own script to update the database table with your own schema. You might use the importCumulusFile article to start you off.

You might also, as I did, want your script to validate what it reads from the daily summary log to ensure only valid numbers and times are stored in your database table, while any invalid inputs are stored as nulls by your script. In my own case, my daily summary table has no solar columns but it does have several additional columns (including the daily increment of chill hours, the cumulative chill hours, the contents of the Weather Diary, the time of the last rain tip, wind bearings as compass characters (e.g. NNW) as well as numerical bearings). When I used Cumulus 1 I wrote a PHP script to find all these additional values, for example it reads the today.ini and month.ini log files as stored in the end of day backup (not the ones being updated for new day in data folder), and the weather diary in log.xml in data folder.

Badge vMx.png MX allows you to specify a different schema in the SQL it generates, but it does not offer that validation feature I just mentioned. I continue to use my Cumulus 1 script (with some changes as for example the weather diary works differently, I am querying SQLite from \CumulusMX\data\diary.db) now I use MX. In the MX standard functionality, you are limited to using web tags for your inputs, and some of those are affected by the end of day process. I tried various content in the custom EOD query, but it did not give me what I need for the scripts that produce my web pages.

MX automatically stores all end of month figures as log files, a feature that Cumulus 1 and 2 lacked, but as yet it does not actually use this extra data, and provides no simple facility to put what is in these files into database tables. There is no end-of-month selection for updates in MX, so you can't easily get as much from dayfile.txt as I do.

When Cumulus is restarted after a break in running

  • It reads the daily log and uses the rainfall totals for each day stored in the daily summary log to calculate the rainfall for this month, and this year/season (see this Cumulus 1 FAQ)
  • Thus you must not have another process attempting access to the daily log when Cumulus is re-starting.
  • For Cumulus 1, back ups of 8 selected log files including dayfile.txt that are copied to start-up folders in the 'cumulus\backup' folder, the last 8 start-up folders only are retained.
  • For Cumulus MX, there are backups of 10 files, the extra ones are the weather diary and Cumulus.ini, that are copied to start-up folders in \CumulusMX\backup\, again there are only 9 kept, unless you back these up somewhere else.

How you can use the daily log

  • If you want to run scripts that use the daily log, it is best if you take a copy first, you can ask Cumulus 1 to take a copy after each update by using the Daily box in the bottom left of the Sites/Options frame within the Internet options screen from the Configuration menu; that will safely take a copy of 'dayfile.txt' after it is updated. This has the advantage it happens even if Cumulus has been stopped and restarted and rollover is happening during catch-up and so not at usual rollover time according to the computer clock. See Cumulus 1 Help for information on using this feature, I add a redirection ">daily_batch.log" in the parameter box alongside so that any output from running the command file I specify in the main box is sent to a log file overwritten in each run; this enables me to see the reason for any failure.
  • Cumulus MX has option to list files to be transferred once a day as part of rollover, so you can use that to generate your extra copy. This has the advantage it happens even if Cumulus has been stopped and restarted and rollover is happening during catch-up.
  • A third party tool "Cumulus Toolbox" can also be used to copy/transfer files at a particular time. Note this cannot tell whether Cumulus has done its rollover at the normal time, or during catch-up.
  • There are other ways to specify that when a file changes it is copied somewhere.
  • The system routines that Cumulus uses to access dayfile.txt require exclusive use of that file, so if you have any other process trying to access that file when Cumulus restarts, when Cumulus processes end of the (meteorological) day, or when a relevant option is selected from View or Edit menus, either your external process or the Cumulus process may fail.
  • Normally if you use any third-party packages like for example "Cumulusutils", the separator used in first line is assumed to be true for all lines.
  • Some third-party tools have to be told what separator you use for dates, before they can read your dayfile.txt.

Viewing or Editing the daily summary log

Both Cumulus 1 and 3 (2 did not) now provide editors where you can see what is in your dayfile.txt log, and if you click on a particular line you can edit the fields in that line, or indeed delete that line.

Important Rules when editing dayfile.txt

If you are editing dayfile.txt outside the Cumulus 1 or MX software, there is the danger of changing something that prevents Cumulus from understanding the file when it next tries to use it.

General Editing Rules

  1. Take a copy of the file that can be reverted to if there is a subsequent problem, and you have messed up the file that Cumulus (1 or MX) is now trying to use.
  2. Take another copy and use that for your editing, don't edit the actual file being used by the software.
    • This prevents any conflicts between access by the software and access by your script or tool being used to modify the file.
    • It also means that you can go back to the last working copy, you can't upset your "revert" copy.
  3. The file must never be edited with a word processor, as they store many control and identification characters that prevent Cumulus correctly reading the values.
    • It is recommended that you use either a specialised "Comma Separated Value" file editor or a text editor, both of these can be easily used.
      • These tools have the advantage that they can cope with different lines having a different number of fields depending on which version number of Cumulus created each line.
    • You can use a spreadsheet tool, but if you do, there may be a number of settings to change from their defaults to ensure the file remains in a readable format for Cumulus.
      • If you do use a spreadsheet, extra field separators may be added at end of shorter lines as these make all lines end up with same number of fields.
    • Don't remove any figures from fields where figures currently exist, only change one entry into another entry in same format.
  4. Cumulus does not accept the concept of nulls, there is nothing that can be placed as a place-holder when the correct figure is not known, and empty fields are not permitted.
  5. All figures must be within the range of sensible figures for that field (no hour 24 or higher, no signed numbers when accepted values must be positive, don't put in 200 for a relative humidity)
  6. Make sure that any editing does not create any blank lines in the file. Cumulus assumes an empty line means end of processing.
  7. Don't add a header line to the file, Cumulus expects all lines to be data lines.

File specific Editing Rules

Open office (editing cumulus log files).png
  1. The file should be saved without "Byte Order Mark", specialised text editors will include a menu where you select the encoding and can select not to include BOM.
  2. All rows must start with date and include at least 14 further fields in correct sequence.
  3. The (meteorological) date format uses two digits for the year.
    • This is one reason why you need to edit this file using an editor that treats all fields as text (a text editor, a CSV editor, or a spreadsheet program that can be instructed not to recognise special field types).
    • For spreadsheet tools (e.g. Calc in Libre Office, or on Microsoft Windows Excel) avoid using default of recognising formats, ensure that such recognition is turned off (see image), as it is likely to change the dates to either a number representing days since e.g. 31 Dec 1899, or to change it to four figure years, and then Cumulus will no longer be able to use the log file.
  4. Remember the month must be the middle figure in the date, USA convention cannot apply within this logfile.
  5. The separator between the three parts of the date should be a '-' hyphen or a '/' slash, it cannot be a space.
    • Whether Cumulus expects a hyphen or a slash is determined by the locale, you must keep to the same locale for the whole file, you cannot change the locale when you do an edit, nor when you update the device running Cumulus.
    • Although, use of comma or point for separating parts of the date is in some locales, and therefore allowed by Cumulus, those locale settings are not recommended as these date separators can cause issues for subsequent edits.
    • If you move your software to a new device, or you change from Cumulus 1 to Cumulus MX (or back), then you must ensure your dates still use the same separator, so all lines are consistent.
  6. Each of the fields from date to the end of the line are separated using the list separator (e.g. a comma or semi-colon) defined for your device. After your editing it must still match what your existing dayfile.txt uses.
    • If you wish to use Excel, or to use "Calc" in 'Apache Open Office', "Libre Office", or similar, you may on opening the file need to pre-select the field separator that is being used now (in this illustration comma is selected, but your file might use semi-colons between fields, don't select commas if your real numbers use comma between integer and decimal parts) and leave "Detect Special Numbers" (or whatever similar feature name your tool uses) unselected. Again third party packages processing dayfile.txt will need to recognise your field separator, and some may need to specify it. Don't forget to also select it when you save the edited file (you probably need to select "save as" or the equivalent in your tool to see the option).
  7. Rows can vary in length but only by missing off fields at the end. The minimum number of fields after the date is 14, the maximum varies between different versions.
  8. Each field has a pre-defined format, and the same format must always be used in that field position.
  9. No fields will accept letters.
    • Some fields (e.g. bearings, solar, humidity) are integers (see #List_of_fields_in_the_file) only take integers. Decimals are not allowed in an integer field, so no comma or full-stop can be within these fields.
    • Most value fields are in real number format using your system/locale decimal notation ("x.y" or "x,y"). Trailing zeroes are not required, so you can put an integer in a real number field, you don't have to have a decimal comma or decimal point.
  10. Although only the date and 14 other fields are mandatory, you cannot skip some fields defaulting them to null is not allowed, so you cannot add fields at the end, without adding all earlier fields.
  11. when you do add fields beyond the 14, or however many already exist, be aware that for most derivatives what you add will represent a lowest or highest value and that must be paired with a time-stamp in the next field.
    • Cumulus will only accept highest/lowest figures if each value has any related time-stamp.
  12. Time stamp fields must always be in format HH:mm i.e. 2 digit hour in 24-hour format, followed by a colon, then 2 digit minutes
      • Be aware you will have problems if you, or your editing software, add seconds.
    • If when editing, you don't know what time to quote, the convention is to use a time-stamp of your roll over time i.e. 00:00, 09:00, or 10:00, if you have not looked up the precise time.
    • Except for wind gust (start of line) where an extra field is fitted in, each time field will immediately follow the value field for that parameter.
  13. Shorter lines can have multiple field separators added at end of row added either when editing within Cumulus or when editing using a spreadsheet tool.
    • Nulls (2 field separators without something between them ',,') are thus allowed at end of line, but are not allowed within the part of the line with values and time-stamps.
    • If you are editing out rogue values and if you do not know the value for a particular field within the line, then type in a zero or 9999 for nulls in integer format and an extreme with opposite value (e.g. -999.9 for a signed decimal maximum, and 9999.9 for a decimal minimum) for nulls in decimal format (replace the full stops with your decimal separator).
    • Beware - if you do insert zero or an obviously wrong extreme value, Cumulus will display those in any editing screen where you wish to update the all-time, monthly-all-time, this month, or this year, extremes. This can make editing by picking values in logs harder.
  14. Cumulus itself will use zero for any parameters (e.g. solar) not provided by your station, and will repeat the last valid value if the station fails to send a value it should provide, so if a station fails to send a value for more than a day, dayfile.txt may show the same value as the previous day.
    • Note that Cumulus will stop if your station fails to send what it considers as a vital reading, like pressure or temperature, so the previous point does not apply in all cases.
  15. The row terminator for Windows is CR LF, ensure any external editor does not change the two character terminator into a single character. Similar rules apply for single character terminators used by other operating systems, don't let windows change a single character terminator into its double character terminator.
    • Problems with terminating characters are intercepted by operating system, before it reaches the software, but may still stop the software understanding the resulting file, so be careful if you edit the file on a different device to that running Cumulus.

Cumulus 1

Cumulus Version 1 Specific This section applies to Cumulus 1.x.y only. The last command in Edit menu is dayfile.txt. This is how you view the dayfile.txt from within Cumulus. This is a text editor, so you can type new values over those currently displayed, insert and delete rows, and it works best when at full screen. Click the Help button for detailed instructions. Cumulus Help is comprehensive.

You can use this Cumulus 1 editor as follows:

  • use insert key to add one or more missing rows (complete days) manually,
  • correct individual values by over-typing,
  • use delete key to remove an entire day (e.g. if you get a 'duplicate' error message),
  • use Create missing button to insert missing rows (complete days) by reading from Monthly_log_files and automatically calculating the best approximations for each field for those missing days.

Dealing with errors identified by the software

If there is an error in dayfile.txt, then it is most likely to be found when you are viewing its data on one of the screens for editing the monthly, annual or all-time extremes. Cumulus 1 will illuminate its Error light if it finds an error in such cases and tell you the line/row number of the first found error, together with some details of the error it found. For example, if a row is blank, a row is duplicated, a field is corrupted, a field does not have an acceptable value, or a field is missing so subsequent fields are to the left of where they should be.

If you do have a 'duplicate' error, you need to decide which row to delete, and whether to copy any values from that row into the row you are keeping to ensure the correct extremes are retained.

Editing externally

See earlier section on this page for the rules and later section for advice on dealing with rogue values.

Create Missing

The Cumulus 1 editor provides a "Create Missing" option where it will, for any dates for which a line does not exist, create a line if it can from reading the detailed log file to extract all values relevant to that day and do the necessary minimum/maximum/total/average calculation for each dayfile.txt field, storing the time from the relevant other log file in any time-stamp field in dayfile.txt. If a particular day does not exist as a row on the daily summary log, then 'create missing' can search the observations in the relevant monthly log, and calculate approximate highs, lows and totals to insert as an extra row in the daily summary log. These are approximate because the actual highs and lows for that day are quite likely to have occurred at moments in-between those that were logged. For Create missing a list of inserted records is produced in dayfileeditlog.txt. If just some fields are wrong in a particular row (meteorological day) on day file, then there is a work around as at all current versions (up to 1.9.4) you can only use 'Create missing' to read from the Monthly_log_files if the whole day (a line starting with that date) is missing in dayfile.txt. Although Cumulus does not recognise the concept of a sensor not being available, it will write solar information even if you don't have a solar sensor; it does have to cope with reading a monthly log file that might have fewer derivatives than it wants (when using Create Missing) and therefore it may not know what to write into dayfile.txt as the calculated value. Cumulus 1 can't write a null value, so it writes zero for values, and "00:00" for time stamps. If you are using a 9am or 10am rollover time, be aware that create missing in Cumulus 1 always inserts 00:00 for null time-stamps, but in normal running Cumulus uses the rollover time for null time-stamps.

Importing data not recorded by Cumulus

As an alternative to manual line insert, in the Cumulus 1 editor, you may wish to use a procedure for importing, and processing, pre-Cumulus observations into Monthly_log_files. Once there is data for required days in monthly logs, Create missing can insert the new rows for those days previously missing in dayfile.txt.

Cumulus 2

Does not provide any viewing functionality.

Cumulus MX

Badge vMx.pngFor Cumulus MX, when you select a line, both Edit and Delete buttons are enabled. There is no way of inserting new lines into dayfile.txt from within MX, nor of changing the dates in the file.

Editing inside MX

Pick Edit, click that and an editing screen pops up, that does not let you change the line number nor the date, but all other fields show their current contents and you can overtype as necessary. Scroll down to see 2 buttons (how they are labelled depends on which version you are using), the left button ignores any edits you have made (it is 'cancel' even if it is labelled 'close'), and the right hand button saves your changes (even if it is labelled 'Edit').

Editing externally

See earlier section on this page for the rules and later section for advice on dealing with rogue values.

MX does not have the capability to recalculate, the values and time-stamp for any entry in dayfile.txt, by reading the detailed log file to extract all values relevant to that day and do the necessary minimum/maximum/total/average calculation. It can be done in a script if you are a programmer. I have done this, but it was not as easy as I thought, the log file you read from may have duplicate times potentially making the calculation harder, and you cannot edit the file as you go along, you basically rename the old file and create a new file with original name as you work through all days changing individual fields whenever you need to.

Editing the file or other Manipulation outside Cumulus

Cumulus Version 1 SpecificApart from bulk changes, Cumulus 1 made editing this log file quite easy. Although the create missing did not work where a line was present for the date, but an individual field needed to be corrected or populated, there was a work around for this.

Badge vMx.pngThe beta versions of MX did not include any feature to view or edit dayfile.txt, so any checking or editing had to take place outside the software. As mentioned above, MX does not provide any way to read, or calculate, values from any other file, nor will it do bulk edits. For any of these, you will need to take a copy of the Cumulus file and manipulate using a script or a spreadsheet processor. Do be careful not to change the encoding, the position of line feeds, the format of any field, the locale, or anything else that might stop MX being able to read the file.


The file is data\dayfile.txt within the directory holding the Cumulus executable, it can be viewed in a text editor, imported into various database systems, or imported into spreadsheets, to manipulate as you wish. Just remember that Cumulus reads it when it is restarted, and updates it as part of the rollover process, so never attempt to work on it either when Cumulus has just been restarted and is checking/updating (and possibly doing a rollover of logs), or around the midnight/9am/10am local rollover time when Cumulus is writing a new row.

Tip: Take a copy of the file before you do any edit outside Cumulus, so you can revert to old file.

Note: Since new versions/builds can add to number of fields, Cumulus will accept lines of 15 fields or more (including without the more recent fields at the end). (Additions by versions are indicated below, you can explore details of earlier versions via the official [Software software/download] page).

Dealing with rogue measurements

Cumulus provides via Configuration menu Calibration screen the ability to screen out spikes (magnitude of differences between one value read and next value read) in data picked up from your weather station. See Cumulus help screen if you decide to use that to cope with some spikes.

If you discover a rogue measurement (perhaps the wind affected your tipping bucket rain gauge or your weather station just reported a corrupted value), on the day it occured, see today.ini or a FAQ for further advice. In general, you need to stop Cumulus, edit the monthly log row containing the dodgy values, edit 'today.ini' and possibly other '.ini' files, looking up the logs indicated below that show the updates with previous high or low.

If the rogue measurement is discovered some days after it occured, then in many cases it will have affected your highs and lows for the current month, month-by-month, current year, and/or all-time. As your first step you should update the appropriate field in the row for the affected date in dayfile.txt. Once dayfile.txt is correct the Cumulus editors will allow you to:

  • update the highs and lows in Alltime.ini by choosing all time records from the Edit menu. See Alltimelog.txt for current and previous values to help you know what rogue value to hunt for and know what the high/low value was before the rogue affected it.
  • update the highs and lows in year.ini by choosing This year's records from the Edit menu.
  • update the highs and lows in month.ini by choosing This month's records from the Edit menu. See Diags for current and previous values of high or low in the current month or the immediate preceding month if the rogue was recorded less than 10 days ago.
  • update the highs and lows month-by-month in monthlyalltime.ini by choosing Monthly records from the Edit menu. Click the Help button for specific instructions on using Reset and the two Copy column header buttons in this Monthly Records (Highs and Lows) Editor to action all rows.
  • Note in each of above 4 editing screens you can:
    1. see the currently stored extremes, and optionally Reset (row by row) to pre-editing value and timestamp.
    2. load the dayfile.txt to view extremes derived from those figures (after your correction of the rogue values) and
    3. optionally Copy (row by row) the logged values (and associated date/time information) into the relevant .ini file.
    4. click the Help button for detailed instructions on using The Records (Highs and Lows) Editors.
    5. store your revised figures by clicking OK (or abandon all your edits by clicking Cancel).
 (Each of these screens is a text editor, and works best when at full screen).
  • create the relevant monthly and/or annual NOAA style report by choosing NOAA Monthly Report or NOAA Annual Report 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 the monthly log files) for period in question. Finally press Save button to store the new or amended report.

Ideally, you will subsequently try to edit the rogue data for the particular time it was logged; see Monthly_log_files#Correcting_any_logged_data_problems, but correcting the daily summary in dayfile.txt must always be the priority.

Using the daily summary log on your web-site

If you upload the log file to your web site then (with the help of JavaScript) you can read the log file to obtain information to show on a web page. You could have a web page that shows a today.htm like table for the last 7 days by combining reading Cumulus web tags with reading from the log file.

Search the Cumulus support forum to see (for example) how others extract information from dayfile.txt to display on their web page a set of fields similar to those shown for 'Yesterday.htm' web page for other dates in the past, such as one year ago.

If you use a script to read what is in the daily summary log file into a database table, or use the functionality in Cumulus MX to upload automatically to a database table, then see Daily_Summary article for information about ALL of the ways to show values from this database table.

Viewing summary figures for a month or period

To view a summary of dayfile.txt for a month, calendar year or selected period, use This month (choose any month, default is month from your computer system date), This year (choose any year, default is year from your computer system date), or This period (choose any start and end dates, default is yesterday calculated from your computer system date), within the View menu.

  • Remember the daily summary log has its records based on rollover to rollover days.
  • In all cases they exclude the today details that are not stored on dayfile.txt until the end of day rollover.
  • If you use 9am or 10am rollover, and choose View This period between midnight and your 9am/10am rollover any day your latest meteorological day is the yesterday in terms of your computer system date that 'This period' tries to display as its default day, and the display will initially appear blank.
  • If you use 9am or 10am rollover, and choose View This month before your 9am/10am rollover on the first day of a new calendar month your latest meteorological month is different to your computer system month 'This month' tries to display as its default month, and the display will initially appear blank.

Most of the displayed results are for observations in the daily summary log, but a few parameters are not in that log and are derived from the monthly logs (e.g. average wind speed) or the weather diary (e.g. count of days with snow lying).

  • On the screen displayed after selecting This month, you can change the month and year required using the options at bottom left, click Update Display and the revised summary will be calculated.
  • On the screen displayed after selecting This year, you can change the year required using the options at bottom left, click Update Display and the revised summary will be calculated.
  • On the screen displayed after selecting This period, you can change the start date and end date then click Update Display to get the equivalent calculations displayed for part of a month or any other period.


Note differences between observation reports on View screens and those available as web tags.

  • Date and time stamps:
    • The day number shown on screen is the meteorological day (changing at rollover and that may be at midnight or 9am/10am) as that date appears in dayfile.txt;
    • A time-stamp (with time and date) given in a web tag quotes a calendar date (always changing at midnight).
  • Reported statistics example:
    • The screen shows total number of dry or wet days in the month;
    • The web tags report longest dry or wet period in the month.


List of fields in dayfile.txt

Variation by Cumulus version

The dayfile.txt has grown as Cumulus's functionality has been extended, the table below shows fields grouped by the Cumulus version when those fields were added.

If you have been using Cumulus for a while, then some lines will be shorter than others, the number of fields per line growing when a new release adds new fields, Cumulus does not in normal operation modify earlier lines, but both Cumulus 1 and MX provide editors where it is possible to modify any line.

There is information earlier in this article about how you might be able to recalculate values to put in for fields that did not exist when any particular line was created.

For your installed build please see dayfileheader.txt (stored within the folder that contains your Cumulus executable), as that will list which fields are available for you.

Information shown in the table

  • The field number is shown starting from zero, this has two advantages:
    • It stresses that the line consists of a date, (that should be a unique identifier, the same date should not be repeated in another line) plus data (mostly numerical, but some values are paired with a time)
    • Numbering starting from zero is consistent with standard indexing used for arrays in programming languages (like JavaScript), so the number shown is the number to quote in any scripts you write to read this file if you just want to examine that particular derivative.
  • The alphabetic column identifiers used by many spreadsheets are shown, please see warnings about using spreadsheets for editing earlier on this page
  • The type of field is shown, you must not put a sign for an unsigned field, you can not specify a decimal point in an integer field, all time fields must use HH:mm format
  • The field description is shown, together with references to where that terminology is explained

List of Fields

Field number Spreadsheet column Field type Description
Included from when dayfile.txt first invented (assumed in first public release 1.0)
0 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)
1 B Unsigned number Highest wind gust speed
2 C unsigned integer Bearing of highest wind gust
3 D 5 characters Time of highest wind gust
4 E signed decimal Minimum temperature
5 F 5 characters Time of minimum temperature
6 G signed decimal Maximum temperature
7 H 5 characters Time of maximum temperature
8 I Unsigned number Minimum sea level pressure
9 J 5 characters Time of minimum pressure
10 K Unsigned number Maximum sea level pressure
11 L 5 characters Time of maximum pressure
12 M unsigned number Maximum rainfall rate
13 N 5 characters Time of maximum rainfall rate
14 O unsigned number Total rainfall for the day
Above here represents the minimum length for every line, a count of 15 items
(The release history between versions 1.2.5 and 1.5.1 was lost by Steve Loft, and for MX in "DataEditor.cs" this addition has " Extended for ???" as a comment)
15 P signed decimal Average temperature for the day
(Wind run was added from version 1.8.4)
16 Q unsigned number Daily wind run
(The next pair of entries were added from version 1.8.9)
17 R unsigned number Highest Average Wind Speed
18 S 5 characters Time of Highest Avg. Wind speed
(The two pairs of humidity entries were added from v 1.9.0)
19 T unsigned integer Lowest humidity
20 U 5 characters Time of lowest humidity
21 V unsigned integer Highest humidity
22 W 5 characters Time of highest humidity
(The next two entries were added from version 1.9.0)
23 X (not documented) Total evapotranspiration (Only valid for Davis stations, shows zero otherwise)
24 Y unsigned Total hours of sunshine (only valid if sunshine sensor connected)
(The next 16 entries were added from version 1.9.1)
25 Z signed decimal High Heat index (added to Cumulus in 1.7.11 only as spot value, not stored)
26 AA 5 characters Time of high heat index
27 AB Signed decimal High Apparent temperature
28 AC 5 characters Time of high apparent temperature
29 AD signed decimal Low apparent temperature
30 AE 5 characters Time of low apparent temperature
31 AF unsigned number High hourly rain
32 AG 5 characters Time of high hourly rain
33 AH) signed decimal Greatest wind chill (high wind speed, low temperature) (added in 1.8.3 as spot value, not stored)
34 AI 5 characters Time of greatest wind chill
(The next two pairs were added in version 1.9.2 beta build)
35 AJ signed decimal High dew point
36 AK 5 characters Time of high dew point
37 AL signed decimal Low dew point
38 AM) 5 characters Time of low dew point
(The next three entries were added in version 1.9.2 Build 1004)
39 AN unsigned integer Today's dominant/average wind direction
40 AO unsigned decimal Heating degree days
41 AP unsigned decimal Cooling degree days
The next two pairs were added in version 1.9.3 build 1036 (these only show valid values if appropriate sensors exist)
42 AQ unsigned decimal High solar radiation
43 AR 5 characters Time of high solar radiation
44 AS unsigned decimal High UV Index
45 AT 5 characters Time of high UV Index
The next two pairs were added in version 3.6.0, 2 more derived values
46 AU signed decimal High Feels Like temperature
47 AV 5 characters Time of high feels like temperature
48 AW signed decimal Low Feels Like temperature
49 AX 5 characters Time of low feels like temperature

Example of the file

An extract of a few lines of the 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