August 2010

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

Mean daily maximum: 19.1
Difference from average:

Mean daily minimum: 9.7
Difference from average:

Mean air temperature: 14.4
Difference from average:

Absolute maximum: 23.4 (20th)

Absolute minimum: 4.2 (31st)

Mean grass minimum: 6.7

Absolute grass minimum: 1.6 (31st)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 16.4

Mean soil temperature at 100cm depth: 15.7

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

Total for the month: 44.8
Difference from average: -22.3

Percentage of the average: 67%

Wettest day: 14.8 (13th)

Number of rain days (>0.25mm): 13

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

3-month total rainfall to 31st August: 182.8
Difference from average: 12.4

6-month rainfall total to 31st August: 286.8
Difference from average: -34.4

12-month rainfall total to 31st August: 704.4
Difference from average: 55.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: %

Sunshine
(all averages 1961 – 1990)

Total for the month: 118.6 hours
Difference from average: -36.9

Percentage of the average: 76%

Mean daily sunshine: 3.8 hours
Difference from average: -1.2

Sunniest day: 9.9 hours (31st)

Number of days with no recorded sunshine: 1 (13th)

Cumulative total sunshine since 1st January: 902.7 hours
Difference from average: -97.8

Wind

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

ISSN1350-483

Comments on August 2010
August was a relatively disappointing month. Daytime temperatures were exactly normal for the time of year whilst nights were colder than usual. Overall, the mean air temperature was just below average, the 4th month this year with below-average temperature. The 12-month running mean remains below 9°C for the 6th month in a row; three years ago, the value was well above 10°C. Curiously, the mean air summer temperature was 14.9°C for the third year in a row; this is somewhat above average, equal 27th warmest since 1850.

August was drier than normal. The wettest day was the 13th with 14.8mm total. The 6-month total is below average for the first time in over a year, whilst the 12-month total is now only a little way above normal. The 3-month i.e. summer total was a very small amount above average, 89th wettest in 161 years.

Though sunnier than July, total hours of bright sunshine were still well below average. The sunniest day was the 31st, a welcome treat right at the end of “summer” as high pressure built from the west. Summer as a whole was very disappointing in terms of sunshine, a total of 375.8 hours, the 8th lowest total since 1882. However, a word of caution: there is some evidence that the recorded hours of bright sunshine may be lower with the automatic weather station than with the traditional Campbell-Stokes glass sphere. This needs further investigation; it may prove that the run of duller summers which has characterised the last decade predates the AWS (installed late 1999) in which case some change in atmospheric circulation must be sought.

Professor Tim Burt
Department of Geography
Durham University