I currently make twice daily observations at 0600 / 1800 GMT (0700 /1900
BST) and have records for my site back to 1982. However as from January 2004
I am CONSIDERING changing the evening observation to 2100GMT / 2200BST, due
to wor / personal circs my main concern IF I do change is am I going to
notice any substantial difference in my records / monthly returns.
My reason for 06/18hrs is simply historical again with work / personal
circs, I'm unfortunately unable to make an 0900hrs observation. 06-18 &
18-06 is a nice 12hr time period between observations but 06 / 21 is 15hrs
and 21 / 06 is 9hrs.

Has anyone changed their obs times (Standard Hours / Non Standard Hours) and
found any major differences - any thoughts / suggestions welcome

Regards

Richard
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Richard Griffith
E-mail

If your minimum temperature is for the period 18 to 06 and max for 06 to 18
the only difference you will notice on switching to 21 hrs is that the mean min
will be slightly lower and the mean max slightly higher, due to including those
minima and maxima that occur between 18 and 21 hrs. There aren't many but
they're not unheard-of. I doubt if the difference over a long period would
amount to more than 0.2°C, almost all of it occurring in winter. My own
practice is day-max night-min, observation hours for this being 08 and 20 hrs
clock time. If you do 24-hr max and min you will notice no difference at all,
naturally, if the morning observation time is unchanged.

Best wishes, Tudor Hughes, Warlingham, Surrey.