August 2021

SUMMARY OF THE METEOROLOGICAL READINGS AT DURHAM UNIVERSITY OBSERVATORY

Temperatures (all temperatures in degrees Celsuis; all averages 1991-2020)
Mean daily maximum: 19.4 Difference from average: -0.4
Mean daily minimum: 11.5 Difference from average: +0.2
Mean air temperature: 15.5 Difference from average: -0.1
Absolute maximum: 22.5 (24th)
Absolute minimum: 6.4 (3rd)
Mean grass minimum: 10.0 Difference from average: +0.8
Absolute grass minimum: 4.6 (3rd)
Mean concrete minimum: 12.1
Absolute concrete minimum: 7.7 (3rd)
Number of ground frosts: 0
Number of air frosts: 0
Mean soil temperature at 300 mm depth: 17.7
Mean soil temperature at 1000 mm depth: 16.2

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

Total for the month: 44.8 Difference from average: -21.8
Percentage of the average: 68%
Wettest day: 10.8 (21st)
Number of rain days (>0.1 mm): 20 Difference from average: +4
Number of wet days (=>1.0 mm):10
3-month total rainfall to 31st August 2021: 142.6 Difference from average: -29.4
6-month total rainfall to 31st August 2021: 267.8 Difference from average: -78.4
12-month total rainfall to 31st August 2021: 778.4 Difference from average: +129.4

Sunshine (all totals in hours; all averages 1981-2010)

Total for the month: 122.0 Difference from average: -44.6
Percentage of the average: 73 %
Mean daily sunshine: 3.9 Difference from average: -1.4
Sunniest day: 8.1 (28th)
Number of days with no recorded sunshine: 1
Cumulative sunshine since 1st January: 1130.9 Difference from average: +15.9
Note that 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 (kph; all data from the West Building roof, Lower Mountjoy campus)

Average wind speed: 4.3
Maximum gust: 41.8 (18th, 12:30, W)

Comments on August 2021

Mean air temperature in August was just below the 1991-2020 average, with the mean minimum just above average and mean maximum just below. The mean air temperature is the 42nd highest for August since 1843 (n=179) so just inside the upper quartile overall, if a little disappointing by modern standards. There were no days above 25 °C, something that has happened in 101 Augusts since 1850. The total of days above 20° C (16) is the 31st equal highest total. There were four days with maximum temperature below 16 °C, but 74 Augusts have had a higher number, so not an unusual month, if disappointingly chilly in cool winds from the north-east quadrant in the second half of the month.

This was the driest August since 2008, the same total this year as in 2009. Despite this, the number of rain days was a little above average; this is the 19th equal highest August total, but there are concerns that the tipping bucket raingauge is overestimating rainfall totals for some reason. August was a dull month, the 26th dullest since 1880, 46 hours less than average (equivalent to 1.5 hours per day).

For summer as a whole, the mean air temperature was 15.8 °C, 0.9 °C above average, the 9th warmest summer at Durham since 1844. Both June (11th warmest) and July (6th warmest) were very warm months; August was relatively disappointing by comparison. Both mean maximum and mean minimum for summer 2021 were 0.9 °C above average. The mean maximum (20.2 °C) is the 16th equal highest on record, whilst the mean minimum (11.5 °C) is the fifth highest on record. Summer rainfall (142.6 mm) was just 75% of the average amount.

Sunshine hours (490) were 19 hours below average.

Emeritus Professor Tim Burt
Department of Geography
Durham University
[email protected]