September 2010

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

Mean daily maximum: 17.8
Difference from average: +1.1

Mean daily minimum: 9.2
Difference from average: +0.5

Mean air temperature: 13.5
Difference from average: +0.8

Absolute maximum: 21.4 (3rd, 9th)

Absolute minimum: 4.9 (25th)

Mean grass minimum: 6.8

Absolute grass minimum: 1.6 (30th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 15.0

Mean soil temperature at 100cm depth: 15.0

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

Total for the month: 75.4
Difference from average: +19.8

Percentage of the average: 136%

Wettest day: 22.8 (7th)

Number of rain days (>0.25mm): 14

Number of wet days (=> 1mm):

3-month total rainfall to 30th September: 182.2
Difference from average: +8.0

6-month rainfall total to 30th September: 293.4
Difference from average: -31.9

12-month rainfall total to 30th September: 765.4
Difference from average: +116.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 82%

Sunshine
(all averages 1961 – 1990)

Total for the month: 110.3 hours
Difference from average: -13.7

Percentage of the average: 89%

Mean daily sunshine: 3.7 hours
Difference from average: -0.4

Sunniest day: 10.8 hours (1st)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 1013 hours
Difference from average: -111.4

Wind

The anemometer remains problematic, no summary results can be provided.

ISSN1350-483

Comments on September 2010
Overall, September was warm, well above average, equal 28th warmest since 1850. There was however, a good deal of contrast between the warm days at the start of the month and the cool, damp days at the end. Rainfall was above average, although not exceptionally so. For the 6th month in a row, a daily fall exceeded 20mm (22.8mm, 7th). The total number of hours of bright sunshine was about the same as in the previous two months, a little below average for September.

Overall, the annual total so far is well below average.

Professor Tim Burt
Department of Geography
Durham University