December 2015

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

Mean daily maximum: 10.3
Difference from average: +3.7

Mean daily minimum: 5.2
Difference from average: +4.1

Mean air temperature: 7.8
Difference from average: +3.9

Absolute maximum: 15.8 (19th)

Absolute minimum: -1.2 (13th)

Mean grass minimum: 3.3

Absolute grass minimum: -1.1 (3rd)

Number of ground frosts: 7

Number of air frosts: 1

Mean soil temperature at 30cm depth: 7.5

Mean soil temperature at 100cm depth: 8.9

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

Total for the month: 124
Difference from average: +66.5

Percentage of the average: 216%

Wettest day: 26.6 (25th)

Number of rain days (>0.25mm): 22

Number of wet days (=> 1mm): 18

3-month total rainfall to 31st December: 294.6
Difference from average: +122.6

6-month rainfall total to 31st December: 502.8
Difference from average: +156.6

12-month rainfall total to 31st December: 742.0
Difference from average: +93.0

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 86%

Sunshine
(all averages 1961 – 1990)

Total for the month: 44.8 hours
Difference from average: -0.8

Percentage of the average: 98%

Mean daily sunshine: 1.4 hours
Difference from average: -0.1

Sunniest day: 5.7 hours (23rd)

Number of days with no recorded sunshine: 10

Cumulative total sunshine since 1st January: 1290.2 hours
Difference from average: -39.1

ISSN1350-483

Comments on December 2015
This was easily the warmest December on record at Durham since 1850 (7.8°C), beating the previous record of 7.3°C in 1988. It was the warmest maximum (0.2°C above the 1988 value); a mean maximum of 10.3°C is more like early April or late October! Likewise, it was the highest mean minimum, a huge 0.7°C above the 1934 mean. There was the equal highest (with 1988) number (20) of December days with a maximum over 10°C. More remarkable was the number of minima over 10°C: since 1900 there had been a total of only 13 December nights with minima over 10°C but December 2015 added 4 to that total; only 1974 had had more than 1 (2)! There was a very low number of ground frosts (7), the third equal lowest total since 1954 and the lowest since 2002.

It was the wettest December since 1978, the 8th highest December total since 1850. The combined total for Christmas Day and Boxing Day was 45.4mm, with 26.6mm recorded on Christmas Day itself, the wettest day of the year and indeed the wettest Christmas Day in Durham since records began. All long-period rainfall totals are now well above average, given three wet months at the end of the year.

Whilst the amount of sunshine was almost average, there were 10 days with no sunshine recorded at all, but this is not an unusual total for the winter months.

Professor Tim Burt
Department of Geography
Durham University