August 2018

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

Mean daily maximum: 19.5
Difference from average: +0.4

Mean daily minimum: 11.6
Difference from average: +1.2

Mean air temperature: 15.5
Difference from average: +0.8

Absolute maximum: 24.3 (5th)

Absolute minimum: 4.2 (31st)

Mean grass minimum: 9.7

Absolute grass minimum: 2.6 (31st)

Mean concrete minimum: 11.3

Absolute concrete minimum: 5.4 (31st)

Number of ground frosts: 14

Number of air frosts: 0

Mean soil temperature at 30cm depth: 17.3

Mean soil temperature at 100cm depth: 16.3

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

Total for the month: 49.8
Difference from average: -17.3

Percentage of the average: 74%

Wettest day: 11.8 (12th)

Number of rain days (>0.25mm): 14

Number of wet days (=> 1mm): 10

3-month total rainfall to 31st August: 136.6
Difference from average: -35.4

6-month rainfall total to 31st August: 324.4
Difference from average: -21.8

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

Humidity
(averages for 09:00 hours GMT)

Relative Humidity: 79%

Sunshine
(all averages 1961 – 1990)

Total for the month: 95.3 hours
Difference from average: -60.2

Percentage of the average: 61%

Mean daily sunshine: 3.1 hours
Difference from average: -1.9

Sunniest day: 8.3 hours (5th)

Number of days with no recorded sunshine: 1

Cumulative total sunshine since 1st January: 984.7 hours
Difference from average: -15.8

ISSN1350-483

Comments on August 2018
August was another warm month but not exceptionally so, only the 36th equal warmest on record. Daytime maxima were less notable than night-time minima; the mean minimum air temperature was the 14th equal warmest since 1850. There were no frosts – there has never been an air frost in August since 1850 – with the last night of the month being the chilliest, the coldest August night since 2014. There were five nights with minimum temperatures above 15°C.

August was drier than average but there was still a high level of cloud cover with the third lowest total of bright sunshine since 1882; only 2006 (87.4 hours) and 1912 (57 hours) have been worse – August 1912 must have felt very dull indeed! This sunshine total is less than one third of the record – 249.8 hours in 1995. Clearly, the cloud cover explains why the night-time temperatures were so high and why, consequently, the overall mean air temperature in August was higher than it might otherwise have been, given daytime temperatures much closer to average.

It was the 7th equal warmest summer at Durham since 1850 and the warmest since 2013. Even warmer summers at Durham include some memorable years like 1933, 1947 and 1976; 2003 remains the warmest summer on record at Durham, a full half a degree Celsius warmer than 2018. It was a dry summer, ranking 37th driest since 1850. Even so, with such a dull August, the summer was below average for sunshine, ranking 93rd lowest in 135 years.

2003 16.2
2006 16.1
1933 16.1
1976 15.9
1947 15.9
2013 15.8
2018 15.7
1983 15.7

Emeritus Professor Tim Burt
Department of Geography
Durham University