July 2013

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

Mean daily maximum: 23.1
Difference from average: +3.8

Mean daily minimum: 12.7
Difference from average: +2.3

Mean air temperature: 17.9
Difference from average: +3.1

Absolute maximum: 28.4 (9th)

Absolute minimum: 8.1 (2nd)

Mean grass minimum: 10.1

Absolute grass minimum: 5.2 (2nd)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 17.1

Mean soil temperature at 100cm depth: 14.5

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

Total for the month: 52.6
Difference from average: +0.8

Percentage of the average: 102%

Wettest day: 39.2 (28th)

Number of rain days (>0.25mm): 8

Number of wet days (=> 1mm): 5

3-month total rainfall to 31st July: 191.6
Difference from average: +36.5

6-month rainfall total to 31st July: 307.0
Difference from average: +11.7

12-month rainfall total to 31st July: 922.8
Difference from average: +273.8

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 75%

Sunshine
(all averages 1961 – 1990)

Total for the month: 174.0 hours
Difference from average: +19.1

Percentage of the average: 112%

Mean daily sunshine: 5.6 hours
Difference from average: +0.6

Sunniest day: 10.6 hours (6th)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 793.0 hours
Difference from average: -51.9

ISSN1350-483

Comments on July 2013
This was the warmest July since 2006 and therefore the second warmest month on record at Durham since 1850. The absolute maximum (28.4°C) on the 9th was the warmest day at Durham since 18th July 2006. Only 5 days had a maximum below 20°C with 5 days above 25°C. The highest night-time minimum was 16.6°C on the 24th. The absolute minimum of 8.1°C has only been exceeded twice in July since 1962: in 1983 and 2004.

The highest daily total of 39.2mm was large by Durham standards but only the wettest day since 18th May! This one day accounted for the monthly total being just above average. There were only 8 rain days, the lowest July total since 2006. The 12-month running total remains very much above average. As with rainfall, sunshine hours were just a little above average too.

Professor Tim Burt
Department of Geography
Durham University