On 9 Jan, 22:51, "Colin Youngs" wrote:
schreef in ...

On 9 Jan, 22:10, Colin Youngs
wrote:

UK min. temps on Thursday nighthttp://tinyurl.com/9uf5sp
*... Yeovilton and Kenley -7.3°C, Aboyne -8.3°C.

A surprisingly cold day max of -1.9°C here, about 15 km north of
Odiham (max -2.3°C), despite a little afternoon sunshine - my coldest
day (day max 09-21h) since 23 Nov 1993. Hope it survives to 0900
tomorrow, slow rise all evg in fog/St after min -6.8°C just before 20h
and now -3°C.
_______________

Today's situation also shows how misleading it can be to quote min. temps
read at 06.00 when the overnight fall in still in progress. * For example,
the Met Office site shows that Yeovilton reported -8.7°C at 09.00http://www.metoffice.gov.uk/weather/uk/sw/yeovilton_latest_weather_gr...
and this figure also appears in the OGIMET list as the 24-hour minimumhttp://tinyurl.com/7bxrkf.

An amateur observer in Flanders reported on the Belgian bulletin board that
his "overnight" minimum of -10.9°C occurred at 11.30 this morning in
freezing fog; another that his minimum of -11.5°C was recorded at 10.00,
also in fog, and was nearly 2 deg. C lower than the minimum of -9.6°C read
at the normal morning observation hour.

Colin Youngs
Brussels

It's been remarked upon previously in this ng, but one of the best
examples occurred on the very coild morning of 31 January 1972 across
England and Wales. At quite a number of sites the lowest temperature
occurred a little after 0900 GMT on 31 January, which then following
normal practice was entered as the min for 1 February. The cold spell
ended shortly afterwards and this temperature observed on 31 Jan
became the February (and annual) minimum at many sites.

There's no perfect method, of course, although personally I favour
00-00h - at least it is unarguable that the extreme occurred within
the 'civil day'. I still tabulate to 0900-0900 GMT for climatological
consistency, but maintain my records for 0900-0900h, 09-21/21-09h and
00-00h. But at this time of year mins read at 0600 are likely to be
quite a bit higher than those read at 0900.

--
Stephen Burt
Stratfield Mortimer, Berkshire