December 2010

Temperatures
(all temperatures in degrees Celsius; all averages 1961 – 1990)

Mean daily maximum: 2.8
Difference from average: -3.8

Mean daily minimum: -3.2
Difference from average: -4.3

Mean air temperature: -0.2
Difference from average: -4.1

Absolute maximum: 8.4 (11th)

Absolute minimum: -10.4 (21st)

Mean grass minimum: -2.7

Absolute grass minimum: -12.7 (21st)

Number of ground frosts: 21

Number of air frosts: 21

Mean soil temperature at 30cm depth:

Mean soil temperature at 100cm depth:

Rainfall
(all totals in millimetres; all averages 1961 – 1990)

Total for the month: 57.2
Difference from average: -0.2

Percentage of the average: 99.6%

Wettest day: 18.6 (9th)

Number of rain days (>0.25mm): 17

Number of wet days (=> 1mm): 12

3-month total rainfall to 31st December: 255.2
Difference from average: +83.2

6-month rainfall total to 31st December: 437.4
Difference from average: +91.2

12-month rainfall total to 31st December: 744.2
Difference from average: +95.2

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 87%

Sunshine
(all averages 1961 – 1990)

Total for the month: 78.6 hours
Difference from average: +33.0

Percentage of the average: 172%

Mean daily sunshine: 2.5 hours
Difference from average: +1.0

Sunniest day: 7.1 hours (6th)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 1250.7 hours
Difference from average: -78.6

ISSN1350-483

Comments on December 2010
Following a cold November, this was one of the coldest Decembers on record. It was equal coldest with 1980 and the coldest since 1878 (-0.9), making it the 3rd equal coldest on record since 1850 – a remarkable result given the generally mild conditions in recent years. The mean maximum was the lowest since 1980. The mean minimum was the first negative value for December since 1995 and the lowest since 1981. This all helps make 2010 the lowest 12-month period mean since the 12 months up to and including January 1997. There was the lowest absolute grass minimum since 1981. There were three days when the maximum was below zero, the lowest maximum being the 3rd (-1.9).

Rainfall (much as snow) was just about average, whilst sunshine was well above average.

Professor Tim Burt
Department of Geography
Durham University