Autumn Weather Forecast

Hello and welcome to my autumn weather forecast, aimed at Reading/Berkshire area but will be general enough to apply to most of south/central England.

First up, the usual caveats – forecasting further than 5 days ahead is generally difficult, so forecasting for a season is very much experimental and can only be talked about in general terms.

Some of this forecast will be wrong. Hopefully more will be right than wrong – that’s my general aim.

That said, both my spring and summer forecasts have gone broadly very well, I suggested summer might be “one for the ages”, and I feel you could describe it as so – it was the hottest on record, with above-average sunshine and below-average rainfall.

Alas, the autumn forecast looks trickier.

Also, thanks to Amanda for the photograph. I had some stunning photographs sent in, but I didn’t want to use anything with too much sunshine in…for reasons you’ll soon read about!

Background Signals

Background signals tend to not have too much use in autumn, but I’ll cover them briefly.

ENSO is currently neutral, though it looks like we may go into La Niña as autumn goes on, which would tend to increase the chance of westerly/north-westerly flows (some suggestions we may go into a significant El Niño next year, but not sure how reliable this is).

Sea surface temperatures remain well above normal around the UK, so that suggests temperatures are more likely to be above normal – any colder weather from the north would likely be diluted.

The hurricane season is the wildcard – prior to Hurricane Erin’s development, I was expecting a drier and warmer start to autumn, which has clearly been blown out of the water. It really was a game-changing system. Might another major hurricane change our weather patterns again? Who knows.

September

September starts unsettled – a brief dry and warm spell for the first weekend, then back to unsettled with spells of wind and rain for the next week, a chance of a named storm.

Around mid-month, there’s a fairly good chance of high pressure trying to build across from the south-west, so generally drier, sunnier and warmer for a time in the second half of the month, though probably it won’t last too long – with the end of the month more likely to be unsettled, with the potential for notably strong winds/heavy rain.

This does assume no major hurricane developing towards USA and changing our patterns.

Overall I expect somewhat above-average temperatures, around average sunshine amounts and somewhat above-average rainfall.

Confidence level of 60%.

October

October more likely starts on the unsettled side, with further spells of wind and rain, though this likely trends further east – which means into week two (give or take) less rain, but probably quite cloudy and breezy, with winds more likely from the north-west so a cooler direction.

Low confidence, but high pressure to our south may have more influence in the second half of the month, so a drier spell though I’m not currently expecting it to be especially sunny or warm – that would depend on positioning of high pressure.

Overall I expect around average temperatures, somewhat below-average sunshine amounts and somewhat above-average rainfall.

Confidence level of 50%.

November

Currently I expect high pressure to have more influence in November, though probably positioned to our south-west or west, which tends to mean cloudy affairs in late autumn.

So broadly a fairly cloudy month, some sunny days at times, some weather fronts at times will likely bring some rain/wind – those more likely in the first half of the month.

Perhaps a greater chance than normal of colder north-westerly or northerly flows later in the month, if La Niña develops, which would at least mean sunnier weather – some overnight frosts possible too.

Overall I expect slightly above-average temperatures (though perhaps cooler than average by day, milder by night – due to the cloud), below-average sunshine amounts and below-average rainfall.

Confidence level of 50%.

Summary And Early Winter Thoughts

So a pretty mixed autumn seems more likely currently – drier towards the end, wetter towards the beginning.

Confidence levels are lower than they were for my summer forecast – there are some conflicting signals in the long range models I use, and not really much to go on in terms of background signals.

Current thoughts for winter are for dry and mild weather in December, more mixed later in winter, with the best chance of cold/snow being in February. But of course, this will likely change…it is sooooo far away.

Happy autumn!