August 2013

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

Mean daily maximum: 20.6
Difference from average: +1.5

Mean daily minimum: 11.4
Difference from average: +1.0

Mean air temperature: 16.0
Difference from average: +1.3

Absolute maximum: 25.1 (1st)

Absolute minimum: 6.5 (7th)

Mean grass minimum: 8.9

Absolute grass minimum: 3.4 (7th)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth: 17.3

Mean soil temperature at 100cm depth: 15.8

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

Total for the month: 71.4
Difference from average: +4.3

Percentage of the average: 106%

Wettest day: 32.6 (5th)

Number of rain days (>0.25mm): 11

Number of wet days (=> 1mm): 8

3-month total rainfall to 31st August: 162.2
Difference from average: -8.2

6-month rainfall total to 31st August: 345.2
Difference from average: +24.4

12-month rainfall total to 31st August: 890.4
Difference from average: +241.4

Humidity
(Averages for 09:00 hours GMT)

Relative Humidity: 77%

Sunshine
(all averages 1961 – 1990)

Total for the month: 131.3 hours
Difference from average: -24.2

Percentage of the average: 84%

Mean daily sunshine: 4.2 hours
Difference from average: -0.8

Sunniest day: 9.5 hours (3rd)

Number of days with no recorded sunshine: 0

Cumulative total sunshine since 1st January: 924.3 hours
Difference from average: -76.2

ISSN1350-483

Comments on August 2013
This was the 18th equal warmest August on record at Durham since 1850 and the warmest since 2004. Whilst the warmest days were at the start of the month, a continuation of the July heat wave, there were nevertheless 18 days with a maximum above 20°C. Combined with an exceptional July and an above-average June, this made for a very warm summer (mean air temperature; 15.8°C): the warmest summer since 2003 and the 6th warmest on record.

Rainfall for the month was just above average, once again because of one especially wet day, in this case 5th August when 32.6mm was recorded, remarkably the 4th day with over 25mm already this year. For the summer as a whole, the rainfall total was just below average. Hours of bright sunshine were below average, indeed the 45th dullest August since 1882. For the summer as a whole, sunshine ranks only 50th out of 130 years’ record.

Using the Davis index of summer weather, which weights sunshine, maximum temperature and rainfall, summer 2013 scores 744 and ranks only as the 34th best summer since 1886. On this basis it was the best summer in Durham since 2006. Maybe it seemed better than it was given the woeful summer of 2012, the 2nd worst on record.

Professor Tim Burt
Department of Geography
Durham University