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October 2021


October 2021

Temperatures (all temperatures in degrees Celsius; all averages 1991-2020)

Mean daily maximum: 14.5 Difference from average: +1.0
Mean daily minimum: 8.1 Difference from average: +1.6
Mean air temperature: 11.3 Difference from average: +1.3
Absolute maximum: 21.1 (8th)
Absolute minimum: 0.5 (16th)
Mean grass minimum: 6.4
Absolute grass minimum: -1.2 (16th)
Mean concrete minimum: 6.9
Absolute concrete minimum: 0.8 (16th)
Number of ground frosts: 1
Number of air frosts: 0
Mean soil temperature at 300 mm depth: 12.7
Mean soil temperature at 1000 mm depth: 13.6

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

Total for the month: 88.5 Difference from average: +29.2
Percentage of the average: 146%
Wettest day: 26.8 (5th)
Number of rain days (>0.1 mm): 18
Number of wet days (=>1.0 mm): 13
3-month total rainfall to 31st October 2021: 177.7 Difference from average: +5.7
6-month total rainfall to 31st October 2021: 362.3 Difference from average: +16.1
12-month total rainfall to 31st October 2021: 757.7 Difference from average: +108.7

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

Total for the month: 92.9 Difference from average: -5.7
Percentage of the average: 94%
Mean daily sunshine: 3.0 Difference from average: -0.2
Sunniest day: 6.5 (21st)
Number of days with no recorded sunshine: 3

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: 5.1
Maximum gust: 74.0 (27th, 02:15, W)

Comments on October 2021

The first half of the month was beset by communication issues between the Observatory AWS and the Met Office. A gap still remains which I hope can be filled in due course; meanwhile grateful thanks to Chris Mueller at the Met Office for supplying the second week of missing data. I am also grateful to Dave O’Hara for supplying some data for the still missing days.

October was a mild month with mean air temperature more than a degree Celsius above average, the 15th warmest on record since 1843. The mean maximum was the equal 14th warmest since 1850, with the mean minimum 11th warmest on record. The absolute maximum of 21.1 °C on the 8th is the 20th equal warmest October days since 1900 (n=3751), the centre of three remarkably mild October days. The minimum of 13.7 C on the 8th is the equal 22nd warmest on record; note that the minimum of the 28th was only one tenth of a degree lower (an actual measurement at the Observatory in this case)!

This was the 39th wettest October since 1850, just into the upper quartile. The wettest ‘day’ was the 5th when 26.8 mm was recorded in the 24 hours ending 0900 on the 6th (By convention the total is ‘thrown back’ to the day before.). The ‘day’ before received 15 mm, with rain starting in the hour after midnight, continuing through to 2300, a combined total in the ‘clock day’ of the 5th of 41.8 mm therefore, equivalent to the 4th wettest October on record. Not surprisingly, sunshine was slightly below average. There was a gust of 74 kph on the 27th at 02:15 with the wind blowing from the west.

Numbers in blue italics kindly provided by Dave O’Hara

Emeritus Professor Tim Burt
Department of Geography
Durham University

[email protected]