October weather: both warmer and wetter than normal

The first two weeks of October brought warm days with the maximum above average every day until the 14^th that brought drizzle in the morning. However, the nights were cool, or even cold, with below average minima from the 6^th to the 12^th and an air frost in the early hours of the 11^th when the thermometer dropped to -0.3C.

Rainfall for this period was sporadic, a couple of dry days interspersed with modest rainfall totals, the heaviest on the 1^st with 4.1mm.

This period also noted for relatively high barometric pressure that dropped to 1002.5mb on the 15^th.

An extensive low-pressure system developed over the Atlantic from 19th, at times extending from the UK to almost America, that was trapped in a loop of the jet stream on its southern flank. The anticlockwise circulation brought southerly winds that contained warm air. The maxima during these days were several degrees above the average as were the overnight minima. A maximum of 18.4C on the 17^th was 3.8C above the 38-year average whilst the minimum of 11.9C overnight of the 19^th/20^th was 4.7C above the long-term average.

After minimal rain in the early hours of the 21^st a very wide and extensive rain band drifted slowly up from the south bringing 12 hours of almost continuous rainfall with a daily total of 31.1mm, which was the wettest day since 3^rd October 2002. Although we had modest rainfall totals earlier in the month this only took the October total to 58.0mm, which was still 31mm below the 38-year average.

The last week or so of October was dominated by a complex system of three low pressure areas to the west of the UK. These areas rotating anti-clockwise maintained the flow of warm, moist air from far south, in the region of North Africa and The Azores. This produced more days with above average maxima with a high of 19.1C on the 27^th, which was the warmest day for a month.

Only one day in October gave us a maximum that was below average, that being the 14^th, which was only 0.2C below average. Analysis of the night-time data showed a very different pattern with numerous nights being cool and several degrees below average due to clearing skies. With no cloud to form a duvet residual warmth escaped into the atmosphere. The coolest night was the 11^th that at dawn saw a low of -0.3C registered. This produced an air frost, the first since 10^th April.

Rainfall each day from the 19^th saw the monthly total rise to equal then exceed the 38-year average on the 26^th, making it only the second month in 2022 to register above average monthly rainfall this year, February being the other.

The month finished with a very warm day on the 29^th when the thermometer rose to 20.8C, which made it the warmest day since 21^st September and a significant 6.2C above the long-term average.

The mean October temperature was 1.65C above the 38-year average. This was principally due to the warm days being 2.5C above average whereas the nights produced a lower average of +0.77C. The average temperature trend for October has been a steady increase since around the year 2000 and has risen from 13.8C to 14.3C during that period.

The considerable rainfall of 11.9mm on the 30^th took the monthly total to 110.9m. This monthly total was 21.3mm above the long-term average and made it only the second above average rainfall month in 2022, February being the other. The overall rainfall total for the period January to October was 447mm, which is 217 below the 38-year average.

www.windrushweather.co.uk