May 2007

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

Mean daily maximum: 14.6
Difference from average: 0.3

Mean daily minimum: 7.0
Difference from average: 1.5

Mean air temperature: 10.8
Difference from average: 0.8

Absolute maximum: 18.3 (22nd)

Absolute minimum: 2.4 (1st)

Mean grass minimum: 6.1

Absolute grass minimum: -1.3 (26th)

Number of ground frosts: 2

Number of air frosts: 0

Mean soil temperature at 30cm depth: 13.1

Mean soil temperature at 100cm depth: 12.1

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

Total for the month: 47.2
Difference from average: -4.6

Percentage of the average:

Wettest day: 13.2 (13th)

Number of rain days (>0.25mm): 14

Number of wet days (=> 1mm): 9

3-month total rainfall to 31st May: 82
Difference from average: -68.4

6-month rainfall total to 31st May: 297.6
Difference from average: -10.9

12-month rainfall total to 31st May: 553.6
Difference from average: -95.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 72%

Sunshine
(all averages 1961 – 1990)

Total for the month: 142.6 hours
Difference from average: -25.9

Percentage of the average: 85%

Mean daily sunshine: 4.6 hours
Difference from average: -0.8

Sunniest day: 12.2 hours (20th)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 610.5 hours
Difference from average: +84.2

Wind

The mean wind speed: 13.3km/h [7.2kt]
Difference from average: +1.1km/hr

The highest gust: 75.9km/h [41kt] from 210° at 09:41 GMT on 9th

ISSN1350-483

Comments on May 2007
After a glorious April, May felt dismal. However, it still turned out to be above average temperature, mainly because night-time temperatures were well above average. Thus, the absolute maximum temperature was the lowest since 1994, yet the absolute minimum equalled that in 2003, both being the highest since 1996. There were only two ground frosts and no air frosts. So, despite everything, the 12-month average still managed to creep up by 0.02°C to (10.77°C), another record for Durham!

Despite 14 rain days and 9 ‘wet’ days, rainfall fell just below average. This contributed to the 15th driest spring on record at Durham since 1852 (82mm) and the driest since 1997. All long-period totals are below average at the moment. April was a relatively poor month for sunshine, the first month in 2007 to be below average. It was also more windy than normal, reflecting the unsettled weather this month.

Professor Tim Burt
Department of Geography
Durham University