September 2008

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

Mean daily maximum: 16.5
Difference from average: -0.2

Mean daily minimum: 9.5
Difference from average: +0.8

Mean air temperature: 13.0
Difference from average: +0.3

Absolute maximum: 20.7 (19th)

Absolute minimum: 4.1 (5th)

Mean grass minimum: 6.5

Absolute grass minimum: -0.6 (22nd)

Number of ground frosts: 1

Number of air frosts: 0

Mean soil temperature at 30cm depth: 15.0

Mean soil temperature at 100cm depth: 15.4

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

NB: gauge faulty – estimate from Met Office website

Total for the month: 90
Difference from average: +34.4

Percentage of the average: 162%

3-month total rainfall to 30th September: 318.3
Difference from average: +144.1

6-month rainfall total to 30th September: 507.5
Difference from average: +182.2

12-month rainfall total to 30th September: 769.1
Difference from average: +120.1

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 90%

Sunshine
(all averages 1961 – 1990)

NB: gauge faulty – estimate from Met Office website

Total for the month: 100 hours
Difference from average: -24

Percentage of the average: 81%

Mean daily sunshine: 3.3 hours
Difference from average: -0.8

Cumulative total sunshine since 1st January: 1116.6 hours
Difference from average: -7.8

Wind

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

ISSN1350-483

Comments on September 2008
We have continued to have problems with the sunshine recorder and, from the middle of the month, with the rain gauge. This is an interim report therefore.

Despite being a disappointing month, September was above average for mean air temperature. Daytime temperatures were below average but this was more than compensated by night-time temperatures being rather more above average. There was one ground frost, the first in September since 2004.

September was another wet month – but not as wet as some places nearby. The very heavy rainfall in the Morpeth area on the 6th stayed too far north to affect Durham; nevertheless there was a high flood on the River Wear because of heavy rain in the Pennines, and water levels stayed high for an unusually long period. With the caveat that the total monthly rainfall is an estimate, it is the first time that the 6-month total has been above 500 since early 2001; the first time that the 3-month total has been above 300mm since December 2000; and the 12-month total highest is since November 2004.

Professor Tim Burt
Department of Geography
Durham University