August 2002

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

Mean daily maximum: 20.6
Difference from average: +1.5

Mean daily minimum: 12.7
Difference from average: +2.3

Mean air temperature: 16.7
Difference from average: +2.0

Absolute maximum: 26.8 (18th)

Absolute minimum: 7.0 (27th)

Mean grass minimum: 11.8

Absolute grass minimum: 5.9 (27th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 17.9

Mean soil temperature at 100cm depth: 16.5

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

Total for the month: 91.8
Difference from average: +24.7

Percentage of the average: 137%

Wettest day: 32.8  (2nd)

Number of rain days (>0.25mm): 12

Number of wet days (=> 1mm): 10

3-month total rainfall to 31st August: 217.8
Difference from average: +47

6-month rainfall total to 31st August: 329.6
Difference from average: +7.6

12-month rainfall total to 31st August: 658.1
Difference from average: +9.1

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 79%

Sunshine
(all averages 1961 – 1990)

Total for the month: 109.7 hours
Difference from average: -45.8

Percentage of the average: 71%

Mean daily sunshine: 3.5 hours
Difference from average: -1.5

Sunniest day: 10.3 hours (27th)

Number of days with no recorded sunshine: 5

Cumulative total sunshine since 1st January: 927.1 hours
Difference from average: 73.4

Wind

The mean wind speed: 17.5 km/h [9.5kt]
Difference from average: +5.8 km/hr

The highest gust: 70.3 km/h [38kt] from 272° at 22:38 GMT on 30th

ISSN1350-483

Comments on August 2002
August was, like June and July, lacking in sunshine, and wetter and windier than usual. Despite this – and somewhat surprising, it was nevertheless the 6th warmest August on record, and the warmest since 1997. This shows that warm nights can make up for the lack of hot days in calculating the average. Even so, daily maximum temperatures were well above the long-term average and our perception of a ‘poor’ August is not at all borne out by the temperature results, only by the sunshine and rainfall data. There were notable falls of rain on the 2nd (32.2mm) and 8th (22.4mm); the former was the wettest August day in Durham since 4th August 1993 when 39.2mm was recorded. Long-period rainfall totals remain above average as a result.

As already noted, the amount of bright sunshine was most disappointing, an hour and a half less each day than on average. There were five days without any sunshine at all, something not experienced in Durham in August since 1989.

Having now checked the rainfall total for 31st July against Environment Agency records, I can confirm the total of 30.6mm recorded at the Durham Observatory (I had some doubts originally about this value, as reported last month). It is notable that another large fall happened only 3 days later, and then another 6 days after that. No wonder the early part of the summer holidays seemed so bad!

Professor Tim Burt
Department of Geography
Durham University