Halloween weather prospects

Halloween is celebrated on October 31st. Its roots are in the ancient Celtic festival of Samhain, which marked the end of summer and the beginning of winter. What weather can we expect this year?

Halloween is celebrated on October 31st. It's roots are in the ancient Celtic festival of Samhain, which marked the end of summer and the beginning of winter. The Celts believed that on this night, the spirits of the dead would return to the mortal world, and large bonfires were lit in villages to ward off any evil spirits that may be at large.

Perhaps those bonfires were also useful to help stay warm because this is a time of the year when the weather can vary a lot in the United Kingdom. In 2008 there was lying snow even in parts of southern England, with several centimetres in the Chilterns on the 28th. If you're interested then take a look at October 2008 snow in south England.  At the other end of the spectrum, 29.9C was recorded at Gravesend, Kent on October 1, 2011. The warmest Halloween on record was in 2014 when 23.6C was reached at Gravesend and Kew Gardens, Greater London.

Will the weather provide a trick or treat?

This year October has been warm and wet relative to the averages. To the 26th the provisional Central England Temperature (CET) is 12.5C which is 2.0C above the 1961-90 average. Severe flooding has occurred, mostly due to the impact of Storm Babet which brought large amounts of rain to parts of the UK which often escape the worst conditions.

In recent days the unsettled weather has continued and computer models are suggesting more of the same for Halloween. However, even when areas of low pressure dominate the UK's weather, drier interludes remain likely. It's a question of timing and when looking several days ahead it becomes difficult to be confident about the details, even if the overall picture is clearly painted. Therefore, the key is to look at a range of computer model forecasts to determine the most plausible outcome. 

Rain pushing up from the south west?

The chart below shows the rain forecasts from the runs in the MOGREPS-G ensemble computer model at 18:00 GMT, Tuesday 31st October. An ensemble model is run many times to show the different possible outcomes at a give time, with the key being to identify the most probable one.

On this chart there is a clear signal for rain to be pushing into south western Britain, but in the rest of the UK many of the forecasts show dry conditions.

Pressure forecast (on the MOGREPS postage stamps select 500hPa / MSLP, plus the date and time) charts show the UK between an area of low pressure pulling away eastwards and one edging in from the west. In between them is a gap in the rain, so despite the unsettled picture there is a reasonable chance of dry conditions in large parts of the UK.

Comparable charts showing temperature forecasts indicate the likelihood of it being chilly in Scotland and perhaps in the northern half of the UK generally. However, in southern and central regions the signs are that it will be milder.

Will it be spooky?

Well it's always spooky on Halloween of course, but perhaps for that little extra a dollop of fog wouldn't go amiss? The chart below shows the fog forecast for 18:00 GMT. Unlike the rain chart it shows the forecast from only one computer model run, so don't attach too much significance to it. However, it suggests fog isn't likely to be widespread, although it could be murky in places.

If widespread fog isn't likely could it be windy? The wind gust chart below suggests the strongest winds will be in south western Britain and the far north.

Winds don't look too problematic in inland areas generally, although with the unsettled pattern it again comes down to the timing of weather fronts and low pressure areas pushing in from the Atlantic. In fact, there are indications of it turning stormy very shortly after Halloween, and it's not out of the question that the strong winds could arrive a little earlier than is currently expected.   

In summary things don't appear too bad in much of the UK at the time of publication, despite the unsettled weather continuing. An area of rain may be pushing up from the southwest; however, many parts of the UK could stay mostly dry.

It is expected to be chilly in Scotland and perhaps in the northern half of the UK, while southern and central regions are likely to be milder. Spooky fog probably won't be widespread, but some places could be murky.

Windy conditions may affect southwestern Britain and the far north, but they are not expected to be problematic in inland areas. Nonetheless, there are indications of stormy weather developing shortly after Halloween, and the possibility of strong winds arriving earlier than expected isn't discounted.

Remember to keep up to date with the short range forecasts (use the forecast bar in the header to select your location) for the latest view.

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