December 2021
SUMMARY OF THE METEOROLOGICAL READINGS AT DURHAM UNIVERSITY OBSERVATORY
December 2021
Temperatures (all temperatures in degrees Celsius; all averages 1991-2020)
Mean daily maximum: 7.4 Difference from average: +0.3
Mean daily minimum: 2.2 Difference from average: +0.8
Mean air temperature: 4.8 Difference from average: +0.6
Absolute maximum: 14.1 (30th)
Absolute minimum: -0.9 (19th)
Mean grass minimum: 1.5
Absolute grass minimum: -2.9 (2nd)
Mean concrete minimum: 1.1
Absolute concrete minimum: -2.7 (11th)
Number of ground frosts: 12
Number of air frosts: 4
Mean soil temperature at 300 mm depth: 6.0
Mean soil temperature at 1000 mm depth: 8.2
Rainfall (all totals in millimetres; all averages 1981-2010)
Total for the month: 66.2 Difference from average: +5.0
Percentage of the average: 108%
Wettest day: 16.8 (4th)
Number of rain days (>0.1 mm): 22
Number of wet days (=>1.0 mm): 16
3-month total rainfall to 31st December 2021: 205.2 Difference from average: +33.2
6-month total rainfall to 31st December 2021: 363.4 Difference from average: +17.2
12-month total rainfall to 31st December 2021: 734.4 Difference from average: +85.4
Sunshine (all totals in hours; all averages 1981-2010)
Total for the month: 37.7 Difference from average: -19.2
Percentage of the average: 66%
Mean daily sunshine: 1.2 Difference from average: -0.6
Sunniest day: 6.7 (16th, 17th)
Number of days with no recorded sunshine: 1
Note that the monthly sunshine total is now calculated from the UKMO E&NE regional total. Daily sunshine totals quoted here and in the data summary are uncorrected.
Wind (kph; all data from the West Building roof, Lower Mountjoy campus)
Average wind speed: 6.1
Maximum gust: 56.3 (1st, 16:30, NNW)
Comments on December 2021
December was a little milder than normal, night-time temperatures the more so. The mean air temperature (4.8 °C) is equal 129th highest on record in the 179 Decembers since 1843. The mean minimum is equal 121st highest and the mean minimum is 126th highest. Whilst temperatures stayed close to average for much of the month, there were some milder days in the middle of the month and three very mild days at the end. The 30th was the 30th equal warmest December day since 1843 whilst the 31st (maximum 13.7 °C) is the warmest New Year’s Eve on record at Durham. The minimum temperature on the 31st (11.0 C) is the 6th equal warmest December night on record. There were fewer air frosts than normal, only 4, the 11th equal lowest total since 1900. There were 12 ground frosts, the 12th equal lowest total since 1874. Rainfall was just a little above average, but it was a dull month, the 41st lowest total since 1880 (n=140), just into the second quartile.
For the year as a whole, mean air temperature was 9.8 °C, 0.4 °C above the 1991-2020 average, the 14th warmest year on record since 1844. The mean maximum temperature was 13.6 °C, equal 13th warmest since 1844, whilst the mean minimum was 5.9 °C, equal 14th warmest on record. The annual precipitation total (734.4 mm) is the equal 42nd wettest on record, with 2019, the wettest years since 2013, but there were no very wet days, the wettest being 26.8 mm on 5th October, the equal 52nd lowest annual maximum total since 1850. Total sunshine hours for the year were very close to average (1473.9 hours).
The data sheet for December 2021 shows that there were two days when sunshine data were not recorded at the Observatory (change of Met Office operating system, no other data lost) and a period of about two weeks when the Geography Department AWS was not working (reason unknown – it started to work again of its own accord!).
Emeritus Professor Tim Burt
Department of Geography
Durham University