September 2004

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

Mean daily maximum: 17.7
Difference from average: +1.0

Mean daily minimum: 9.7
Difference from average: +1.0

Mean air temperature: 13.7
Difference from average: +1.0

Absolute maximum: 25.8 (6th)

Absolute minimum: 4.4 (25th)

Mean grass minimum: 5.3

Absolute grass minimum: -1.3 (25th)

Number of ground frosts: 2

Number of air frosts: 0

Mean soil temperature at 30cm depth: 15.2

Mean soil temperature at 100cm depth: 15.6

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

Total for the month: 19.6
Difference from average: -36

Percentage of the average: 35%

Wettest day: 3.2 (15th)

Number of rain days (>0.25mm): 13

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

3-month total rainfall to 30th September: 240.6
Difference from average: +66.1

6-month rainfall total to 30th September: 396.6
Difference from average: +70.3

12-month rainfall total to 30th September: 732.1
Difference from average: +83.1

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 76.3%

Sunshine
(all averages 1961 – 1990)

Total for the month: 131.7 hours
Difference from average: +7.7

Percentage of the average: 106.3%

Mean daily sunshine: 4.4 hours
Difference from average: +0.3

Sunniest day: 10.8 hours (8th)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 991.2 hours
Difference from average: -133.2

Wind

The mean wind speed: 14.1km/h [7.6kt]
Difference from average: +1.8km/hr

The highest gust: 75.9km/h [41kt] from 286° at 09:50 GMT on 20th

ISSN1350-483

Comments on September 2004
Unlike August, September was a dry month, with only a third of normal rainfall. Even so, there were 13 rain days. It was a mild month, with all three temperature measures one degree above average. Sunshine was a little above average too, only the second such month in a rather dull and disappointing year.

Professor Tim Burt
Department of Geography
Durham University