December 2017

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

Mean daily maximum: 6.9
Difference from average: +0.3

Mean daily minimum: 1.5
Difference from average: +0.4

Mean air temperature: 4.2
Difference from average: +0.3

Absolute maximum: 12.4 (7th)

Absolute minimum: -6.7 (11th)

Mean grass minimum: -1.1

Absolute grass minimum: -10.2 (11th)

Mean concrete minimum: 0.8

Absolute concrete minimum: -3.3 11th)

Number of ground frosts: 20

Number of air frosts: 12

Mean soil temperature at 30cm depth: 5.0

Mean soil temperature at 100cm depth: 7.4

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

Total for the month: 34.0
Difference from average: -23.5

Percentage of the average: 59%

Wettest day: 8.0 (1st)

Number of rain days (>0.25mm): 14

Number of wet days (=> 1mm): 13

3-month total rainfall to 31st December: 140.6
Difference from average: -31.4

6-month rainfall total to 31st December: 349.2
Difference from average: +3.0

12-month rainfall total to 31st December: 667.5
Difference from average: +18.5

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 85%

Sunshine
(all averages 1961 – 1990)

Total for the month: 74.7 hours
Difference from average: +29.1

Percentage of the average: 164%

Mean daily sunshine: 2.4 hours
Difference from average: +0.9

Sunniest day: 6.6 hours (28th)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 1229.1 hours
Difference from average: -100.2

ISSN1350-483

Comments on December 2017
December was above average temperature but not greatly so, the equal 68th warmest December since 1850. It was both sunny and dry. This was the 37th driest December on record, drier than last year but wetter than 2014; and all three quite unlike the very wet December 2015. This was the 6th sunniest December since 1882 but only the sunniest since 2014 (which is the sunniest December on record: 96 hours).

Emeritus Professor Tim Burt
Department of Geography
Durham University