December 2018

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

Mean daily maximum: 8.1
Difference from average: +1.5

Mean daily minimum: 2.9
Difference from average: +1.8

Mean air temperature: 5.5
Difference from average: +1.6

Absolute maximum: 12.4 (6th)

Absolute minimum: -1.2 (25th)

Mean grass minimum: 1.0

Absolute grass minimum: -3.5 (25th)

Mean concrete minimum: 1.0

Absolute concrete minimum: -2.9 (4th)

Number of ground frosts: 11

Number of air frosts: 5

Mean soil temperature at 30cm depth: 5.8

Mean soil temperature at 100cm depth: 7.7

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

Total for the month: 43.8
Difference from average: -13.7

Percentage of the average: 76%

Wettest day: 9.2 (15th)

Number of rain days (>0.25mm): 19

Number of wet days (=> 1mm): 10

3-month total rainfall to 31st December: 156.8
Difference from average: -15.2

6-month rainfall total to 31st December: 309.4
Difference from average: -36.8

12-month rainfall total to 31st December: 627.4
Difference from average: -21.6

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 85%

Sunshine
(all averages 1961 – 1990)

Total for the month: 61.1 hours
Difference from average: +15.5

Percentage of the average: 134%

Mean daily sunshine: 2.0 hours
Difference from average: +0.5

Sunniest day: 6.4 hours (9th)

Number of days with no recorded sunshine: 5

Cumulative total sunshine since 1st January: 1298.4 hours
Difference from average: -30.8

ISSN1350-483

Comments on December 2018
December was a mild month; the mean air temperature was the 22nd highest since 1850. Both the mean maximum and mean minimum were also well above average, equal 18th and equal 15th highest respectively (since 1900). Even so, there were 11 ground frosts and 5 air frosts. The lowest maximum was only 3.8°C (14th) and the maximum exceeded 10°C on nine days including five of the last six days of the month. It was a sunny month and so rainfall was below average, as expected; it was the 25th sunniest December at Durham since 1882 and the 67th driest since 1850.

Emeritus Professor Tim Burt
Department of Geography
Durham University