July 2008

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

Mean daily maximum: 20.1
Difference from average: +0.8

Mean daily minimum: 11.2
Difference from average: +0.8

Mean air temperature: 15.4
Difference from average: +0.8

Absolute maximum: 26.1 (27th)

Absolute minimum: 6.9 (21st)

Mean grass minimum: 8.8

Absolute grass minimum: 3.7 (21st)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 16.6

Mean soil temperature at 100cm depth: 15.2

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

NB: gauge faulty – estimate from Met Office website

Total for the month: 134
Difference from average: +82.5

Percentage of the average: 260%

Wettest day: 27.6 (6th)

Number of rain days (>0.25mm): 15

Number of wet days (=> 1mm): 13

3-month total rainfall to 31st July: 223.8
Difference from average: +68.7

6-month rainfall total to 31st July: 352.4
Difference from average: +57.1

12-month rainfall total to 31st July: 654.8
Difference from average: +5.8

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 80%

Sunshine
(all averages 1961 – 1990)

NB: gauge faulty – estimate from Met Office website

Total for the month: 180 hours
Difference from average: +25.1

Percentage of the average: 116%

Mean daily sunshine: 5.8 hours
Difference from average: +0.8

Cumulative total sunshine since 1st January: 906.6 hours
Difference from average: +61.7

Wind

The mean wind speed: 9.3km/h [5kt]
Difference from average: -2.3km/hr

ISSN1350-483

Comments on July 2008
Temperatures were well above average, but not exceptionally so, mainly due to some warm days at the end of the month.

July was the 4th wettest on record since 1850. Nevertheless, July has been much wetter on three occasions: 1930 (183.9mm), 1867 (184.9mm) and the record-holder, 1888 (206.6mm). Remarkably, the daily rainfall total exceeded 20mm three times: 23mm on the 31st, 23.8mm on the 9th and 27.6mm on the 6th. Even so, there were only 15 rain days, two fewer than last year. All long-period totals are now above average.

Once again, the sunshine recorder did not function so I have had to estimate sunshine hours using the Met Office website. As last month, wind speed was well below average.

Professor Tim Burt
Department of Geography
Durham University