July 2004

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

Mean daily maximum: 18.9
Difference from average: -0.4

Mean daily minimum: 10.9
Difference from average: +0.5

Mean air temperature: 14.9
Difference from average: -0.1

Absolute maximum: 24.6 (30th)

Absolute minimum: 8.2 (6th)

Mean grass minimum: 10.1

Absolute grass minimum: 5.5 (26th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 16.6

Mean soil temperature at 100cm depth: 15.1

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

Total for the month: 64.2
Difference from average: +12.7

Percentage of the average: 125%

Wettest day: 13.6 (5th)

Number of rain days (>0.25mm): 19

Number of wet days (=> 1mm): 16

3-month total rainfall to 30th July: 156.2
Difference from average: +0.7

6-month rainfall total to 30th July: 322.2
Difference from average: +25.7

12-month rainfall total to 30th July: 678.5
Difference from average: +29.5

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 75.1%

Sunshine
(all averages 1961 – 1990)

Total for the month: 117.8 hours
Difference from average: -37.1

Percentage of the average: 76.1%

Mean daily sunshine: 3.8 hours
Difference from average: -1.2

Sunniest day: 10.2 hours (26th)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 736.1 hours
Difference from average: -108.8

Wind

The mean wind speed: 9.4km/h [5.1kt]
Difference from average: -2.1km/hr

The highest gust: 64.8km/h [35kt] from 250° at 12:42 GMT on 14th

ISSN1350-483

Comments on July 2004
July was a dull, wet month of only average temperature, disappointing in other words. Mean maximum temperatures were below average, the lowest since 2000 but, not surprisingly given the cloudy weather, mean minimum temperatures were above average, though still only the lowest since 1999. Overall, mean air temperature was just above average, but we only have to go back to 2002 to find an equally disappointing July!

July rainfall was a little above average; again, 2002 was wetter. All long-term totals are now above average. The wettest day was the 5th with 13.6 mm. Rain fell on 19 days, a relatively high total, and the largest number since 1998. It was a dull month too, with over an hour less sunshine per day on average than normal, though only the dullest since 2001. The sunniest day (26th) recorded only 10.2 hours. July was nevertheless a relatively calm month with wind speeds somewhat below average.

Professor Tim Burt
Department of Geography
Durham University