Britain is more likely to be hit with Christmas storms than festive snow thanks to a freak shift in the Polar stratosphere.
Weather experts agree on the imminent occurrence over the Arctic of a Sudden Stratospheric Warming (SSW).
The event usually triggers cold conditions in Europe and the UK, as with 2018’s Beast from the East mega freeze.
But an unusual twist could put Britain in line not for snow and ice, but for gales and downpours.
Mild temperatures and unsettled cyclonic bouts from the Atlantic are likely to give Santa’s sleigh a rocky ride.
Jim Dale, meteorologist for British Weather Services, said: “A Sudden Stratospheric Warming event such as what we are expecting soon may not always lead to cold weather.
“Rather than bringing cold winds and snow from the north and the east, such as in 2018, it can push this over America and put Britain at risk of unsettled weather.
“Although it is still a way off, this is looking more likely with this one.”
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SSW events are triggered when shifts in global wind patterns disrupt the circular flow of air high over the North Pole.
Air from the stratosphere, around 15 to 20 miles from ground level, falls closer to Earth, warming rapidly on its descent, coining the term ‘sudden warming’.
This can push bitterly cold air from the Arctic Region and into the lower latitudes, close to Europe and America.
SSW events usually have a fortnight lag between the warming and any changes in weather, meaning it would be felt around the third week in December.
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Met Office meteorologist Aidan McGivern said: “A Sudden Stratospheric Warming is likely to happen soon, and there is a chance that it will have implications for the UK weather.
“Typically, there is a 70 per cent chance that after an SSW, we get colder weather in the UK, but three out of ten times it doesn’t happen.
“But we are not talking about impacts until the second or third week of December, and that is a bit far off to tell whether there will be impacts from the SSW.
“But the temperature trend for the next 10 days is that it is going to get warmer before any potential cooldown.”
Also unusual is the early arrival of this year’s SSW, an event that happens every two to three years.
And in the meantime, Britain’s temperatures will yo-yo between balmy and cold, McGivern added.
He said: “We are expecting a minor SSW, but what is interesting is how early it is happening, we don’t often expect them at the end of November or the start of December.
“It is going to get milder as we get to the end of the week, so there is the potential for a mild spell.
“It is likely that it is unsettled, with spells of rain but higher than average temperatures, and there is no clear signal on whether the SSW will have an impact on the UK.”
Met Office meteorologist Alex Deakin added: “The stratosphere is suddenly warming up, but I wouldn’t get too excited if you are after snowfall.
“We are going to see the UK turn a little warmer this week before potentially some heavy rain across the south this weekend.”
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