September 2001

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

Mean daily maximum: 16.0
Difference from average: -0.7

Mean daily minimum:  9.7
Difference from average: +1.0

Mean air temperature:  12.9
Difference from average: +0.2

Absolute maximum: 21.1 (6th)

Absolute minimum: 7.1 (17th)

Mean grass minimum: 8.3

Absolute grass minimum: 5.3 (17th)

Number of ground frosts: 0

Mean concrete minimum: 9.3

Mean ground temperature at 30cm depth: 14.4

Mean ground temperature at 100cm depth: 15.7

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

Total for the month: 68.1
Difference from average: +17.5

Percentage of the average: 134%

3-month total rainfall to 30 September: 142.7
Difference from average: -31.8

6-month rainfall total to 30 September: 246.7
Difference from average: -88.6

12-month rainfall total to 30 September: 778.7
Difference from average: +129.7

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 79.3%

Sunshine
(all averages 1961 – 1990)

Total for the month: 72.2 hours
Difference from average: -51.8

Percentage of the average: 57%

Mean daily sunshine: 2.4 hours
Difference from average: -1.7

Sunniest day: 8 hours (8th)
Number of days with no recorded sunshine: 6

Cumulative total sunshine since 1st January: 1059.2 hours
Difference from average: -65.3

Wind

The mean wind speed: 12.8km/h [6.9kt]
Difference from average: +0.5km/hr

The highest gust: 72.2km/h [39kt] from 276° at 16:24 GMT on 7th

ISSN1350-483

Comments on September 2001
Mean air temperature was slightly above the long-term average. Maximum temperatures were disappointing but night-time minima were above average. This suggests a cloudy month, and indeed the mean sunshine figures show a disappointing total, well below the average (by nearly 2 hours per day).

Our automatic raingauge did not function during September so the rainfall data reported here are based on figures supplied by the Environment Agency for nearby Barker Heugh. Rainfall was above average, but not greatly so.

This is an opportunity to thank Helen Goldie, who retired at the end of September, for her carefully attention to the Durham University meteorological records over many years. I hope to continue her good work.

Professor Tim Burt
Department of Geography
Durham University