"Steve J" wrote :
On 7 Dec, 12:57, "Philip Eden" wrote:

That looks like an error Steve ... the national record for December
is only 18.3°C, and that was strongly f?hn assisted in northwest
Scotland!

All the Midlands sites in the Monthly Weather Report for Dec 1899
have maxes of 54-56°F.

Yes Philip, you may be right; in fact, I had already put a question
mark next to the daily maximum temperature of 66F for the 5th on a
photocopy of the original hand scripted weather log.

There is another reading of 18.3C (65F) as a maximum for the.7th
December 1900 - this too is under scrutiny - what do you think?

The monthly highs in the Midlands range from 55°F at Edgbaston
to 59°F at Cirencester ... none of them on the 7th, which suggests
another reading or transcription error.

If we ignore December maxima in 1899 & 1900, our warmest December day
is 16.4C in 1915.

This one's intriguing (16.4 isn't the equivalent of a whole number
fahrenheit)
but Coventry was appearing in the MWR by this time, and it is given as
56°F. If this is your station, Steve, then the observation has been
quality controlled.

I'd certainly agree with John about the kind of errors that do crop up.
Having leafed through thousands of pages of original observations,
5deg and 10deg errors and transpositions are the most common, but
I've also seen 6 for 0 and vice versa, 5 for 2 and v.v., and 7 for 1
and v.v. More difficult are the 1deg errors on Celsius thermometers
(an error I occasionally make) - for example reading 17.3 as 18.3.

Philip