April 2005

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

Mean daily maximum: 11.6
Difference from average: -0.2

Mean daily minimum: 4.1
Difference from average: +1.0

Mean air temperature: 7.9
Difference from average: +0.9

Absolute maximum: 16.0 (30th)

Absolute minimum: -1.2 (19th)

Mean grass minimum: 1.9

Absolute grass minimum: -3.7 (19th)

Number of ground frosts: 11

Number of air frosts: 1

Mean soil temperature at 30cm depth: 9.2

Mean soil temperature at 100cm depth: 8.8

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

Total for the month: 66.4
Difference from average: +18.9

Percentage of the average: 140%

Wettest day: 39.8 (15th)

Number of rain days (>0.25mm): 10

Number of wet days (=> 1mm): 4

3-month total rainfall to 30th April: 144.4
Difference from average: +3.8

6-month rainfall total to 30th April: 201.2
Difference from average: -117.7

12-month rainfall total to 30th April: 650.6
Difference from average: +1.6

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 75.5%

Sunshine
(all averages 1961 – 1990)

Total for the month: 144 hours
Difference from average: +10.8

Percentage of the average: 108.1%

Mean daily sunshine: 4.6 hours
Difference from average: +0.2

Sunniest day: 10.8 hours (22nd)

Number of days with no recorded sunshine: 3

Cumulative total sunshine since 1st January: 326.5 hours
Difference from average: -31.3

Wind

The mean wind speed: 16.1km/h [8.7kt]
Difference from average: +2.2km/hr

The highest gust: 77.8km/h [42kt] from 186° at 07:44 GMT on 6th

ISSN1350-483

Comments on April 2005
Mean air temperature in April was above average, but this masks a contrast between mean daily maximum – a little below average – and mean daily minimum – well above average. This suggests a relatively cloudy month – certainly sunshine was only a little above average and it was, overall, a wet month. In fact, there were only 10 rain days, and the large total was accounted for by two very wet days – 14th and 15th when a total of 58.8mm fell, a notably large two-day total for Durham.

The 3-month and 12-month rainfall totals are now back to average levels but the 6-month total remains well below average, reflecting the dry ‘extended’ winter.

Professor Tim Burt
Department of Geography
Durham University