January 1987. This month saw an exceptional cold spell resulting from an easterly airstream which began in earnest on the 9th, with cold air starting to feed in from the 7th. Before that here was a wet start to the month. Then the maximum at Aviemore was -5C on the 8th and 9th. On the 9th, an anticyclone anchored over Scandinavia forced a depression moved SE over Britain leading to strong NE to E winds across England on the 10th, and bringing exceptionally cold air from an unusually cold Europe.
I remember the forecast from the night before very clearly; the cold was predicted accurately well in advance. The coldest air reached England on the 11th. Maxima on the 12th January were commonly around -6C; -8C across large parts of the south; the day probably was equal to or lower than the previous lowest maximum in London (see also January 1841 and 1867). For many places this was the coldest day of the century.
For example, Warlingham (Surrey) recorded a 12 hour daily maximum of -9.2C, a 24 hour maximum of -9.0C, with minima of -12.4C and -10.0C either side. Quite often it was clear and sunny, but the cold air crossing the warm North Sea led to a very high snowfall on the eastern coast, with the snow starting in the evening: 45 cm of snow settled at Southend, and 50 cm fell even in Cornwall. The Charing Cross to Dover train took 13 hours to get to Ashford.
The highest temperature in Britain on the 12th was +0.1C at the Butt of Lewis; all of mainland Britain remained beneath freezing. The following night was unsurprisingly very cold everywhere, widely beneath -10C, and with -16.0C recorded at Aviemore. There was more heavy snow on the 13th and 14th. There were slightly higher temperatures on the 15th, as the extreme cold slowly eased its grip. A slow thaw began on the 20th. In parts of the south there were 14 consecutive sunless days from the 14th (to the 28th), in many places setting a new “dullness” record. Here are the noon temperatures from Gatwick from the 7th to the 20th: 0, -2, 1, -1, -5, -7, -7, -3, -2, -1, -3, -3, -3, -1.
There was severe frost damage to plants on the Isles of Scilly. The lowest reading of this exeptional spell was -23.3C at Caldecott (Leics.) on the 13th. There was freezing rain in the south Midlands. Generall it was a very dry month – the driest since 1964. This was the last significantly cold month of the century (with +0.8C CET, the last month beneath 1C before 2010).