Still warm and wet as the evenings draw in

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Autumn leaves in late evening sunshine, Epping Cemetery, October 2021 (Roger Emmens)

Still mild and wet as the evenings draw in – a review of October 2021

This year continues its generally warm and wet theme, as October proved to be another rainy month. October is our wettest month on average, but this was our 5th wettest of our 37 years of records, with 112.4mm (161% of the average). For the sixth month in a row, we had a wettest day of more than 20mm – indeed, in October we had two, with 25.2mm on 5th and 27.8mm on 20th. With two months to go, we have already comfortably exceeded our average annual rainfall, despite April being our driest month on record!

But actually it wasn’t a bad month – much of it was dry and settled, with the wettest and windiest weather associated with three areas of low pressure that passed through, on 2nd-5th, 19th-21st and 29th-31st, which can clearly be seen in the graphs.

Sunshine was often at a premium, and we recorded only 36 hours of sun (defined as solar radiation greater than 300 W/m2). Surprisingly it was not a particularly windy month: the strongest gust was 28mph on 31st, which is third lowest of the ten years of detailed wind speed records we have for October.

As for the temperatures, we continue the trend of warming clearly evident in our records. This October did not have any heatwaves, but it continued to be mild virtually throughout the month, and the mean temperature proved to be the 7th warmest of our 37 years of records, at 12.2°C that was 1.2°C above the long term average. The warmest day of the month was the 19th with a relatively modest peak of 19.4°C, but we recorded the second highest minimum for a November day of 15.6°C on the 19th, and we have not yet had the first frost of the Autumn.

Perhaps that’s to come in November? That’s normally the first month of the winter with a frost. The latest date ever for our first air frost of the winter was 18th December, back in 1984!

MeasureUnitMinimumAverageMaximumAverage minAverage maxTotal
Relative humidity%548797
Wind source (most common/highest gust)SectorSSSE
Wind speedmph2.72817.1
Rain daily accumulationmm3.627.8112.4
Barometric pressurehPa984.71015.81032.3
Solar irradiance during daylightW/m²137710463
Sunshine (sunny if irradiance > 300 W/m2)Hours1.25.536.5

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