The Weather Day

Just like the Australian Bureau of Meteorology (BOM), a day in the life of Eric's weather begins at 9 am and ends a nano second before 9 am the next day. This start/end time is especially relevant for some summary weather statistics for the day, such as maximum temperature and total rainfall.

What does BOM use exactly? When the maximum temperature over the preceeding 24 hours is determined at 9 am on a particular day, BOM records this as the maximum temperature for the previous day. In contrast, the minimum temperature for the previous 24 hours is recorded as the minimum for the date of the 9 am observation or determination, not the previous day. Similarly, the total rainfall for the previous 24 hours is recorded against the date at the 9 am observation, as is the daily wind run. And there are more exceptions or qualifications to the "rule" - the maximum gust is recorded midnight to midnight for a given day. A gust, by the way, is defined by BOM as "any sudden increase of wind speed of short duration; typically a 3 second time period." While this BOM definition of a gust is typical of other authorities, many, perhaps most, use the midnight to midnight definition of a day for all summary statistics, which of course takes care of the issue of their date.

Eric, records all such summary values determined from the recordings of the last 24 hours to 9 am against the previous day. This is because the Cumulus software has no other option if the 9 am start time is chosen. I can't really blame it - to try and take cognizance of BOM's rules would make the programming rather more complicated.

In this website, Eric makes a handful of exceptions to this rule and these are marked accordingly in the appropriate place:
* indicates since midnight.