August 2020

Temperatures
(all temperatures in degrees Celsius; all averages 1981 – 2010)

Mean daily maximum: 19.5
Difference from average: -0.3

Mean daily minimum: 12.1
Difference from average: +1.1

Mean air temperature: 15.8
Difference from average: +0.4

Absolute maximum: 26.9 (11th)

Absolute minimum: 3.4 (31st)

Mean grass minimum: 10.8

Absolute grass minimum: 0.7 (31st)

Mean concrete minimum: 11.3

Absolute concrete minimum: 0.5 (31st)

Number of ground frosts: 0

Number of air frosts: 0

Mean soil temperature at 30cm depth:

Mean soil temperature at 100cm depth:

Rainfall
(all totals in millimetres; all averages 1981 – 2010)

Total for the month: 110.8
Difference from average: +50.2

Percentage of the average: 183%

Wettest day: 30.8 (27th)

Number of rain days (>0.2mm): 21

Number of wet days (=>1.0mm): 13

3-month total rainfall to 31st August: 249.0
Difference from average: +77.0

6-month rainfall total to 31st August: 297.4
Difference from average: -48.8

12-month rainfall total to 31st August: 729.6
Difference from average: +80.6

Sunshine
(all averages 1981 – 2010)

Total for the month: 131.1 hours
Difference from average: -35.6

Percentage of the average: 79%

Mean daily sunshine: 4.3 hours
Difference from average: -1.1

Sunniest day: 9.2 hours (8th)

Number of days with no recorded sunshine: 2

Cumulative sunshine since 1st January: 1209.9
Difference from average: 127.0

Note: the monthly sunshine total is now calculated from the UKMO E&NE regional total.
Daily sunshine totals quoted here and in the data summary are uncorrected.

Wind
(all data from West Building roof, Lower Mountjoy)

Average wind speed: 5.3kph

Maximum gust: 57.9kph (14:45, 21st, SW)

ISSN1350-483

Comments on August 2020
Despite feeling somewhat depressing, this turned out to be the 25th equal warmest August since 1850. It started well enough with 10 of the first 12 days above 20°C; the absolute maximum of 26.9°C on the 11th is the 49th equal warmest August day since 1900. However, the latter part of the month was disappointing with none of the last 10 days above 20°C. Several days suffered from cool north easterlies, with disappointing low maximum temperatures, for example the 13th (16.1°C) and 14th (16.2°C). The maximum of just 12.7°C on the 29th is the 23rd equal lowest for any August day since 1900. The minimum of 3.4°C on the last night of the month is 23rd equal coldest August night since 1900.

It was the 22nd wettest August on record, the wettest August since 2011, and there was the 10th equal highest number of rain days. The total of 30.8mm on the 27th is the 31st wettest August day since 1850; the rain fell steadily from 17:00 on the 27th to 08:00 on the 28th, including 5.2mm for the hour ending 03:00 on the 28th. A \”deluge\” was reported in Durham on the afternoon of the 23rd, including 6.2mm at the Observatory between 14:00 and 15:00 GMT; the day\’s total was 14.2mm. For this event, the West Building AWS received 8.6mm in the same hour, of which 7.2mm fell between 15:15 and 15:30. Sunshine in August was well below average, the 37th least sunny August since 1882. Notwithstanding the inadequate exposure of the solar radiometer, not one day recorded as much as 10 hours of bright sunshine.

For the summer as a whole, whilst feeling relatively dreary except for some brief heat waves, this was actually the 20th warmest at Durham since 1850, its mean air temperature (15.1°C) being 0.3°C above average. This was largely because of mild nights, with the 7th equal highest mean minimum since 1900 (11.1°C), 0.7°C above average; the mean maximum (19°C) was 0.2°C below average, the 66th lowest on record. It was a wet summer, the total of 249mm being 70mm above average, the 20th highest summer total since 1850. Sunshine was well down on average, just 417 hours, 86 hours fewer than expected, the 20th lowest summer sunshine total since 1882. Taken together, the Davis Summer Index confirms the disappointing summer weather, the 29th worst summer in 120 years, just into the bottom quartile.

Emeritus Professor Tim Burt
Department of Geography
Durham University