The readings returned representing Today are based on the settings of your rollover time. Please refer to the main CumulusMX Wiki for further details. Cumulus allows some control over the time that “Today” begins:

You can define the log rollovertime. Choose between 9am or midnight. For the weather diary feature SnowDepthHour The default SnowDepthHour is 8 Readings from your weather station are assigned to the “Today” based on 3 options for Meteorological day starting at 9:00 am, based on winter time, so switching to 10:00 during Daylight Saving (summer) time, or starting at 9:00 am, all year round, or aligned with calendar days, so today starts at midnight The independence of the start time for weather diary and weather station related web tags needs to be remembered when labelling web tags from the two tables below. It was assumed that you would use 9 a.m. as start time for both, but not care when snow fell, as it often has in the UK, after Summer Time has begun, so weather station tags were by default reporting from 10 a.m. local time and snow as at 9 a.m. In MX, if you choose 9 a.m. (optionally 10 a.m. in summer) for rollover, so all the standard derivative are assigned to the date the meteorological day starts as Today, but the sunshine hours recorded against today will be from midnight on the said date. Weather Diary This first table lists all the web tags available for reporting what is recorded in the weather diary. Just to be clear, the web tags shown below, will report data for previous day if the current time is before the snow depth hour setting, and report data for the current day if the current time matches the snow depth hour or is later. Webtag name Function <#Option_showSnow> Displays the value of the Display Options⇒General Options⇒Snowfall: this option enabled will display snowfall data from the Weather Diary on the default web site <#snowdepth> Meteorologists report snow depth in cm, so this is default unit for Cumulus. Snowdepth should include the snow24h amount so automatic measurement (by laser) always is the correct amount! If there is no entry in Weather Diary for the day explained above, reports zero. Input is to 2 decimal places to accommodate inches as unit (see station settings⇒ unit settings in CMX). <#snowcomment> Displays the comment field of the weather diary. <#snow24hr> Fresh snow which fell the past 24 hrs. If this amount is subtracted from snowdepth you find the melt/compression of the previous snow. <#DiaryThunder> <#DiaryHail> <#DiaryFog> <#DiaryGales> These tags return “true”, “false”, or “-” if no diary entry exists. This null value can be overridden with the usual nv= parameter. These tags take an optional parameter of the date to be queried: date=YYYY-MM-DD <#SnowAccumSeason> queries the Weather Diary for the current snow season total snow fall. The tag takes an optional parameter `y=YYYY` which you can use to specify the snow season starting year for which you want the total. Today.ini These tag names relate to the current Meteorological day and they are populated from information held in today.ini; Where a tag name reports a value specific to a past time in today-so-far, there will also be a tag name that can give the time of day, shown in same row of table below. For those that cover whole day so far, the final column contains “n/a”.

There is some inconsistency in naming with “T” not included in all tag names, “T” is used in conjunction with “H” or “L” as a suffix for extreme values/time-stamps, but a prefix “T” can identify today's value and also signify a time-stamp.