Halloween set to be warmest on record: trick or treat?

You may step outside tomorrow across England and Wales and think that someone has put a spell on the weather, with hazy sunshine expected and temperatures well above average.

Temperatures across East Anglia and south east England are likely to reach 21C in a few places, which would make it the warmest Halloween on record.

The current warmest Halloween on record for the UK was back in 1968, when Dartford in Kent reached a balmy 20C.

Why so warm?

At the moment, the orientation of the jet stream is giving a weather pattern that puts much of the UK in a flow of warm air from the south.

The jet stream sits where the greatest temperature difference between warm and cold air occurs, so as it moves around, it determines which places sit in cold or warm air.

It is currently dipping southwards in the mid-Atlantic, scooping up warm air from the Azores, then pushing it towards the UK, ahead of an area of low pressure.

How unusual is the expected warmth?

It would be fair to say that the 21C expected in some places tomorrow is pretty impressive for late October.

The warmest October day on record for the UK is 29.9C, however that was recorded at the beginning of the month, at Gravesend in Kent on 1 October 2011.

November’s warmest day on record is 21.7C, which is a little above the highest temperatures likely across eastern parts of England tomorrow.

It just happens that a spell of notable warmth is falling on the day Halloween itself. But in the grand scale of October as whole, it’s not that big a deal.

What about Halloween evening?

For those of you venturing out for trick or treating, the weather for all parts of the UK is looking mild between 6pm and 9pm.

Weather for 6pm on Halloween evening

Temperatures will be around 13-16C for Scotland and Northern Ireland, with 16-19C across England and Wales – temperatures that would be remarkable in the daytime at this time of year.

Whilst much of England and Wales will be dry, Scotland, Northern Ireland and the far west of England and Wales will see rain arriving through the evening.

Don’t forget, you can get the latest forecast on the Channel 4 Weather website. I’ll also be posting updates on Twitter – @liamdutton