July 2012

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

Mean daily maximum: 18.1
Difference from average: -1.2

Mean daily minimum: 10.6
Difference from average: +0.2

Mean air temperature: 14.4
Difference from average: -0.5

Absolute maximum: 22.8 (24th)

Absolute minimum: 5.8 (31st)

Mean grass minimum: 9.4

Absolute grass minimum: 2.5 (31st)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 16.0

Mean soil temperature at 100cm depth: 14.1

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

Total for the month: 97.6
Difference from average: +46.0

Percentage of the average: 189%

Wettest day: 24.8 (6th)

Number of rain days (>0.25mm): 16

Number of wet days (=> 1mm): 14

3-month total rainfall to 31st July: 309.0
Difference from average: +129.0

6-month rainfall total to 31st July: 463.4
Difference from average: +117.2

12-month rainfall total to 31st July: 779.8
Difference from average: +130.8

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 84.1%

Sunshine
(all averages 1961 – 1990)

Total for the month: 89.3 hours
Difference from average: -65.6

Percentage of the average: 57.7%

Mean daily sunshine: 2.9 hours
Difference from average: -2.1

Sunniest day: 8.8 hours (21st)

Number of days with no recorded sunshine: 2

Cumulative total sunshine since 1st January: 749.7 hours
Difference from average: -95.2

ISSN1350-483

Comments on July 2012
July 2012 had exactly the same mean air temperature as July 2011, another disappointing below-average month, the second in a row. Days were cooler but nights warmer than a year ago. There were only 9 days when the air temperature went above 20°C.

For the 4th month in a row, rainfall was well above average. Indeed, these four months have been the third wettest of any consecutive 4 months since records began (435.4mm), beaten only by November 1978 to February 1979 (453.7mm) and in 1867 (May – August: 503mm). In just 4 months, we have gone from a major deficit to a large excess!

As with June, July was another very poor month for sunshine, well below average; this was the 5th lowest total for any July since 1882 and the worst since 1968.

Professor Tim Burt
Department of Geography
Durham University