April 2010

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

Mean daily maximum: 13.5
Difference from average: +2.5

Mean daily minimum: 3.6
Difference from average: +0.5

Mean air temperature: 8.6
Difference from average: +1.6

Absolute maximum: 19.8 (28th)

Absolute minimum: -1.8 (2nd)

Mean grass minimum: 0.8

Absolute grass minimum: -5.0 (2nd)

Number of ground frosts: 16

Number of air frosts: 3

Mean soil temperature at 30cm depth: 9.2

Mean soil temperature at 100cm depth: 8.6

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

Total for the month: 12.4
Difference from average: -35.1

Percentage of the average: 26%

Wettest day: 3.8 (2nd)

Number of rain days (>0.25mm): 7

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

3-month total rainfall to 30th April: 148.2
Difference from average: +8.0

6-month rainfall total to 30th April: 445.4
Difference from average: +126.7

12-month rainfall total to 30th April: 824.2
Difference from average: +175.2

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 72%

Sunshine
(all averages 1961 – 1990)

Total for the month: 138.5 hours
Difference from average: +5.3

Percentage of the average: 104%

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

Sunniest day: 11.5 hours (1st)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 380.8 hours
Difference from average: +23

Wind

The anemometer remains problematic, no summary results can be provided.

ISSN1350-483

Comments on April 2010
April was a warm month with daytime temperatures in particular well above average. It was the = 10th highest mean maximum in 111 years of record and the = 15th highest mean air temperature for April since 1850. Nevertheless, the 12-month average was again just below 9°C (8.97°C).

It was the 11th driest April since 1850. [Only 2.2mm in 1938!] It was the driest month since February 2008.

Curiously, for the second month in a row, the sunniest day was the 1st!

Professor Tim Burt
Department of Geography
Durham University