The anticyclone present at the end of November continued into December but soon moved away. Calm, sunny days with three air frosts and one ground frost at night continued for the first five days, -1.3°C on 2nd being the lowest. No more air frosts occurred for the rest of the month and just one ground frost on 11th and two in the last week.

This all changed on the night of 5th/6th when low pressure caused by Atlantic depressions took over and 4mm rain fell. These conditions continued until 21st. Daytime temperatures rose from single to double figures ranging 12.2°C on 6th, the maximum for the month, down to 6.8°C on 17th. Night minima depended on the amount of cloud cover, ranging from 9.9°C on 19th (the warmest night) down to 1.9°C on 10th, with a ground frost. During this period, from 5th to 21st some rain was recorded on every day but one. Totals were mostly single figures in millimetres but 10.9mm on 12th, 11mm on 14th and 14.4mm on 19th were the highest. Much of the rain fell overnight and days were a mixture of cloud with sunny periods. The mainly south-westerly winds were generally no more than moderate.

On 22nd the barometer began to rise rapidly, reaching a peak on 28th as anticyclonic conditions moved in. With mainly cloudy conditions there was little change in temperature between day and night. Only the night of 29th/30th brought a ground frost, falling to 1.5°C. From 25th to 27th several narrow fronts moved through lasting about an hour at a time, bringing a total of just 2.3mm of rain.

The average temperature for December was 1.65°C above my 30-year average but down on December 2018. The year as a whole was 1.12°C above average, just about the same as 2018.

The total rain for the month was 89.4mm, 139% of my 25-year average, slightly less than November. October was the wettest month this year, the place held, on average, by November. The total for the year was 666.6mm, 97.7% of my 25-year average and the wettest since 2013.

December 2019 was a month of short, dark days without extremes; mainly mild and damp but beginning and ending with colder, dry weather.

Mike Wilkins

25 year Rainfall averages are from 1992-2016
30 year Temperature averages are from 1981-2010