"whitehead1972" wrote:

Mornin' all, Having set up a weather station, complete with
traditional Met Office standard rain gauge, sheathed grass minimum
thermometer (I haven't yet sourced a Stevenson screen if anyone on
here has a spare!) it occured to me how many on here manage to take
readings at exactly 9am every day. With the school run and other tasks
it is frequently impossible for me to make it back in time and I end
up sometimes taking the readings at, for example, 9.20am.
How many of you have taken readings before or after 9am and recorded
them as "9am" - you can e-mail me in confidence.

If you aim to take your readings as close to 0900 (it should be GMT)
as possible, that is all you can do. If, for any reason, I am more than
15 minutes away from the nominal ob time I simply make a note of it
in the book. If 0900GMT is unattainable because of work or other
commitments, you have two options (at least): either select a time
- 0800, say, or 0730, or even 1800 - which you can stick to on most
days, and call that your terminal hour, or use any automated equipment
you may have to apportion rainfall (and the occasional max or min
temp) to the correct climatological day.

Official networks have never been able to guarantee that all their
co-operating observers carried out the observations at the nominal
time (on some days it could be quite clear that this was not the case)
although the majority probably succeeded most of the time.

Philip