May 2003

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

Mean daily maximum: 15.5
Difference from average: +1.2

Mean daily minimum: 7.7
Difference from average: +1.2

Mean air temperature: 11.6
Difference from average: +1.7

Absolute maximum: 22.4 (31st)

Absolute minimum: 2.4 (10th)

Mean grass minimum: 7.1

Absolute grass minimum: 1.6 (10th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 12.4

Mean soil temperature at 100cm depth: 11.1

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

Total for the month: 39.6
Difference from average: -12.6

Percentage of the average: 76%

Wettest day: 9.8 (3rd)

Number of rain days (>0.25mm): 15

Number of wet days (=> 1mm): 8

3-month total rainfall to 31st May 2003: 68.8
Difference from average: -82.4

6-month rainfall total to 31st May 2003: 229.4
Difference from average: -79.9

12-month rainfall total to 31st May 2003: 638.8
Difference from average: -10.2

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 70%

Sunshine
(all averages 1961 – 1990)

Total for the month: 152.5 hours
Difference from average: -16

Percentage of the average: 91%

Mean daily sunshine: 4.9 hours
Difference from average: -0.5

Sunniest day: 11.3 hours (31st)

Number of days with no recorded sunshine: 2

Cumulative total sunshine since 1st January: 669.7 hours
Difference from average: +143.3

Wind

The mean wind speed: 14.8km/h [8kt]
Difference from average: +2.4km/hr

The highest gust: 70.4km/h [38kt] from 210° at 0:44 GMT on 8th

ISSN1350-483

Comments on May 2003
May was another warm month: with both mean daily maximum and mean daily minimum 1.2°C above average, it is not surprising that the mean air temperature is well above the long-term mean (+1.7°C) too. It was the warmest May since 1999 and 8th equal warmest on record since 1852. The warmest May on record is 1952 (12.4°C). The maximum temperature of 22.4°C is not exceptional; the minimum recorded (2.4°C) is a little more notable, but even so only the highest since 1999.

Rainfall was a little below average. The three-month total to 31st May remains exceptionally low, and while not as extreme at the end of April, is still the 50th lowest in the series of 1819 3-month totals since 1850.

Sunshine fell a little below average, but nevertheless the total so far in 2003 remains well above the long-term mean.

Professor Tim Burt
Department of Geography
Durham University