Winter 1837-38 was a remarkable winter as it went from the exceptionally mild during the second half of December to the exceptionally cold during January.

The first half of December 1837 was cold but it turned very much milder during the second half of December and indeed it became exceptionally mild and this lasted until the end of the month.

17th-31st December: 8.3

The start of the New Year was mild but it turned much colder on the 5th and this was to herald a severe cold spell that culminated in the coldest CET day ever recorded. On the 10th of January 1838, there was a serious fire at the Royal Exchange in London and the cold was that intense that hoses from  fire appliances sent to the scene had to be thawed out. By the 12th, the cold had grown even more intense and ice skaters took to lakes and ponds as all water surfaces became iced over. Frosts were very severe and highly penetrating. The 20th was truely exceptional with a CET daily mean of -11.9C. Minima were as low as -20C or below in many places and maxima were well below 0C, probably as low as -10C.The weather warmed up temporarily on the 22nd  but the cold was back and the cold waxed and wane through February but the intensity of the cold was nowhere near as bad as it was in January.

December: 5.3 (+1.7)
January: -1.5  (-3.9)
February: 0.4 ( -3.6)

17th-31st December: 8.3
1st-15th January: -1.3

8th-21st January: -5.1

8th January-23rd February: -1.7

CET daily mean
18th December: 9.5
20th January: -11.9

A difference of 21.4C within 5 weeks. 

From the Dorset County Chronicle of 25th January 1838

"Christchurch- such was the intensity of the frost last week, that the Christchurch Serpentine, alias the Stour, bordering on this town was so completely frozen as safely to admit a very large concourse of persons of the town and neighbourhood to assemble on the ice on Friday last. Beauty and fashion promenades on one part of the river; whilst a party was playing a most animated game of cricket on a distant part."

"Poole, 24th Jan. 1838- the weather we experienced for the fortnight ending on Saturday last was intensely cold. With many fluctuations, but generally increasing in intensity, the cold in Friday night was so excessive as hardly to have been paralleled in the recorded meteorlogy of the town. On Friday evening it was observed that large crystals of ice were spreading over the waters of the harbour and on Saturday morning the whole of the vast body of tidal water comprised in the harbour was covered with a sheet of ice varying one to three inches in thickness. The freezing of this estuary of the sea, subject as it is to the motion of the tide has not before occurred for the last forty nine years. Fortunately, a thaw commenced on the afternoon of Saturday, or a total interruption must have taken place in the navigation of the harbour. During the prevalence of the severe weather, immense numbers of wild fowl frequented the shores and neighbourhood of the harbour and were shot in unprecedented quantities"

A letter from The Times on Jan 16 1838.

10F = -12.2C, in London.

From Jan 18:

And from the same writer as the first letter, a few days later:

4F = -15.6C. If the estimate of 6F colder out of town is correct, that is -2F or -18.9C. The daytime max on 20 Jan was 16F or -8.9C.

The location (Paragon, New Kent Road) is only 1 mile from London Bridge, so even then it would have been quite an urban location.

Pity there's no charts available for that era - but, given the reports seem to be from the south, I'd expect it to be an easterly feed

Google books now has a fair few meteorological registers digitized for this period. Here is a detailed one:

https://books.google.co.uk/books?id=koMEAAAAQAAJ&printsec=frontcover&dq=nautical+magazine&hl=en&sa=X&ved=0ahUKEwjhsc3EoJXKAhUFvhQKHfwQAKIQ6AEIIDAA#v=onepage&q=meteorological%20journal&f=false

Page 143-144

A lot of the reports from that month mention thick powdery snow on the 17th and squally snow showers with thunder involved.

That must mean the upper 850hpa temps crossing the North Sea were of extreme cold to favour such convection. Indeed in the report the 17th shows force 7 NNE winds so a deep cold pool over Scandi must have crossed the North Sea into the UK at this point.

The morning of the 20th saw very calm winds so clearly an anticyclone with clear skies and snow cover must have favoured the low mininima.

An interesting read. No prizes for guessing why you chose this time to post it!

I see that the severe cold gave the townsfolk the perfect opportunity to slaughter the local bird-life......

Anybody got any extrapolated or parameterised charts from Dec/Jan 1837/38? Would be a fascinating comparison.

I looked through the Times archive but they didn't do synoptic charts back then. (I'm not sure exactly when they started.)

I did find this in the Sunday Times of Jan 28 1838 though... would that modern-day weather reports were so poetic!

Hmm... not sure why it has squished up like that. Here is the link: http://i.imgur.com/m6yAkNk.png

I just checked and The Times carried daily weather charts from April 1 1875. They were pretty basic back then. Here is the very first:

Squashed again. Original at http://i.imgur.com/EEdMrVg.png