October 1921 was an incredible month for autumn warmth! The first third of the month saw a phenomenal heat wave which recorded temperatures quite widely into the mid-to upper twenties in the first ten days of the month. In fact, 25C was reached or exceeded on eight of the first ten days of the month. Unsurprisingly, it recorded a very high CET of 12.8C.

October 1921 is also the sunniest October on record too.

Temperatures peaked at 28.9C in London on both the 5th and 6th. These two days held the October temperature record until 1985 and later 2011. London also recorded 27.8C on the 9th during another push of heat. This is the latest date in the year where 80F has been recorded in the UK. Thunderstorms also broke out in the heat in parts of the west.

The heat wave mostly ended on the 11th-12th, when cooler autumnal air moved in from the Atlantic. However another burst of heat arrived around the 18th where parts of the South East recorded 24.4C.

Interesting article from the Met Office here: http://www.metoffice.gov.uk/media/pdf/n/l/Oct1921.pdf

And amazingly,  the CET for November 1921 was only 4.6C, giving a drop in mean temp of 8.2C in just one month!  I wonder if this is the largest ever fall in the CET record from one month to the next?     November 1921 itself was about 2.5C below average, meaning that a record breaking heatwave in the October was followed by exceptional cold a month later!

I guess if the synoptics pump all that heat into the higher latitudes then HLB, and the associated cold, will be encouraged to follow.

Is it time to pull out the warm/dry October theory/stories yet?

There was a bigger drop in 1807 between the October and November of 8.5C from 11.4C to 2.9C

Outstanding stuff. The funny thing is, the local pattern does not look all that far off that for a time next week - but the airmass doesn't look anywhere near as warm in the lower levels of the atmosphere, plus it will be about a week later in time than was the case in 1921, and there are signs that the Atlantic will muscle in after just 4-5 days.

So - not on a par at all, unless the models are underestimating both the low-level warmth and the resilience of the ridge (and even then we'd probably not make it due to the shorter days).  To get even close, we'd need a better-defined trough to the west of the UK that digs right down west of Iberia (i.e. just like in 1921).