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.
MANCHESTER SUMMER INDEX for 2021: 238
Timelapses, old weather forecasts and natural phenomena videos can be seen on this site
http://www.youtube.com/channel/UCgrSD1BwFz2feWDTydhpEhQ/playlists