September 2002

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

Mean daily maximum: 17.3
Difference from average: +0.6

Mean daily minimum: 9.5
Difference from average: +0.8

Mean air temperature: 13.4
Difference from average: +0.7

Absolute maximum: 21.1 (3rd, 12th)

Absolute minimum: 4.6 (24th)

Mean grass minimum: 7.6

Absolute grass minimum: 1.9 (24th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 15.3

Mean soil temperature at 100cm depth: 15.8

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

Total for the month: 25.2
Difference from average: -30.3

Percentage of the average: 46%

Wettest day: 15.0 (10th)

Number of rain days (>0.25mm): 6

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

3-month total rainfall to 30 September 2002: 201
Difference from average: +26.5

6-month rainfall total to 30 September 2002: 315.4
Difference from average: -10.9

12-month rainfall total to 30 September 2002: 605.2
Difference from average: -43.8

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 80%

Sunshine
(all averages 1961 – 1990)

Total for the month: 102.6 hours
Difference from average: -21.4

Percentage of the average: 83%

Mean daily sunshine: 3.4 hours
Difference from average: -0.7

Sunniest day: 10.2 hours (2nd)

Number of days with no recorded sunshine: 3

Cumulative total sunshine since 1st January: 1029.7 hours
Difference from average: -94.8

Wind

The mean wind speed: 8.0 km/h [4.3kt]
Difference from average: -4.3 km/hr

The highest gust: 57.4 km/h [31kt] from 203° at 14:31 GMT on 5th

ISSN1350-483

Comments on September 2002
September 2002 was another warm month, but although well above average, Septembers in 1998, 1999 and 2000 were all warmer. Overall, September 2002 was the 27th warmest on record since 1850. It was also a dry month, the 30th driest September on record, and but for 15mm on the 10th would have been very dry indeed. Even so, sunshine was below average and the total for the year so far is nearly 100 hours below the expected level. Wind speed was well down on average too.

Dave O’Hara from the Ferryhill Weather Station kindly alerted me to the fact that we are now very close to breaking through the 10°C average for the first time since records began. When I checked, we seem in fact to have got there! The 12-month average up to and including June 2002 is 10.02°C, exactly the same as for the 12-month average to September 2002. By contrast, the average in 1850 was only 7.95°C. Out of interest, the long-term average in Oxford (where I used to run the weather station) is 9.6°C – amazing to think that Durham is currently warmer than the south Midlands average. As noted before, we are clearly in the middle of a very remarkable warm period!

Professor Tim Burt
Department of Geography
Durham University