August 2007

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

Mean daily maximum: 19.2
Difference from average: 0.1

Mean daily minimum: 10.6
Difference from average: 0.3

Mean air temperature: 14.9
Difference from average: 0.2

Absolute maximum: 25.5 (5th)

Absolute minimum: 5.4

Mean grass minimum: 7.4

Absolute grass minimum: 1.3 (9th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 16.8

Mean soil temperature at 100cm depth: 16.0

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

Total for the month: 30.6
Difference from average: -36.5

Percentage of the average: 46%

Wettest day: 17.2 (14th)

Number of rain days (>0.25mm): 8

Number of wet days (=> 1mm): 6

3-month total rainfall to 31st August: 254.4
Difference from average: 84.0

6-month rainfall total to 31st August: 336.4
Difference from average: 15.6

12-month rainfall total to 31st August: 728.4
Difference from average: 79.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 76%

Sunshine
(all averages 1961 – 1990)

Total for the month: 152.6 hours
Difference from average: -2.9

Percentage of the average: 98%

Mean daily sunshine: 4.9 hours
Difference from average: -0.1

Sunniest day: 11.2 hours (23rd)

Number of days with no recorded sunshine: 4

Cumulative total sunshine since 1st January: 989.4 hours
Difference from average: -11.1

Wind

The mean wind speed: 12.4km/h [6.7kt]
Difference from average: 0.9km/hr

The highest gust: 61.1km/h [33kt] from 180° at 23:14 GMT on 2nd

ISSN1350-483

Comments on August 2007
Despite a bad press, August temperatures were just above average. It was the coolest August since 1999 but still ranks 56th warmest in 158 years; of course, many of the warmest Augusts have been in recent years. There was the lowest minimum temperature since 2000 but only the lowest maximum since 2005 (when the maximum was only 22.1°C). For the summer as a whole, it was overall 0.35°C above average, the coolest since 2000, but still ranking 57th warmest in 158 years.

August was a dry month, well below average. There was the fewest number of rain days since April. All long-term totals remain above average. Despite the low August rainfall total, it was still the 12th wettest summer on record, but only the wettest since 2004. Despite low rainfall, sunshine was just about average.

Perhaps it was the combination and high rainfall and average temperatures that made the summer seem so poor in many people’s eyes? To test this, I calculated the Davis (1968) index of summer weather, which weights temperature, rainfall and sunshine to produce an overall index of how good the summer weather has been. On this basis, 2007 ranks 12th worst since 1886 and the worst since 1987. 1976 tops the list with 2006 ranked 8th. Clearly the contrast between last year and this is what has strengthened the sense of disappointment.

Professor Tim Burt
Department of Geography
Durham University