December 2001

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

Mean daily maximum: 6.4
Difference from average: -0.2

Mean daily minimum: 0.3
Difference from average: -0.8

Mean air temperature: 3.4
Difference from average: -0.5

Absolute maximum: 14.9 (1st)

Absolute minimum: -4.4 (31st)

Mean grass minimum: -0.5

Absolute grass minimum: -4.1 (26th)

Number of ground frosts: 23

Number of air frosts: 17

Mean soil temperature at 30cm depth: 4.6

Mean soil temperature at 100cm depth: 7.7

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

Total for the month: 35
Difference from average: -22.4

Percentage of the average: 61%

Wettest day: 5.6 (24th)

Number of rain days (>0.1mm): 17

3-month total rainfall to 31st December: 122.3
Difference from average: -49.6

6-month rainfall total to 31st December: 265
Difference from average: -81.4

12-month rainfall total to 31st December: 566.6
Difference from average: -82.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 84.2%

Sunshine
(all averages 1961 – 1990)

Total for the month: 51.5 hours
Difference from average: +5.9

Percentage of the average: 113%

Mean daily sunshine: 1.7 hours
Difference from average: +0.2

Sunniest day: 5.9 hours (31st)

Number of days with no recorded sunshine: 12

Cumulative total sunshine since 1st January: 1250.6 hours
Difference from average: -78.7

Wind

The mean wind speed: 14.8 km/h [8.0kt]
Difference from average: -0.2 km/hr

Highest gust: 101.9 km/h [55kt] from 277° at 06:47 GMT on 28th

ISSN1350-483

Comments on December 2001
Compared to previous months, December was cooler than normal, particularly at night, and mean air temperature fell half a degree Celsius below the average. With rainfall below average and sunshine above average, this suggests cloud-free weather with sunny days and frosty nights, and there were indeed 23 ground frosts and 17 air frosts. Although there were 17 rain days, none was very wet, with Christmas Eve recording the highest daily total of only 5.6mm.

Professor Tim Burt
Department of Geography
Durham University