Britain could be hit by a fresh blast of freezing temperatures after a “Sudden Stratospheric Warming” of the earth’s atmosphere.
The disturbance, which happened in the past few days, is associated with low temperatures and “greatly increases the risk of wintry weather”, the Met Office said.
An SSW happens about 30 miles up when a disturbance disrupts the jet stream and pushes air in the opposite direction, reversing its direction. As the air compresses it can warm by up to 50C in just a few days.
A Met Office spokeswoman said: “It happened a couple of days ago but it takes 10 days of so for the implications to be felt on the surface.
“It usually indicates more settled conditions but it’s too early to say.”
The Met Office said that a “a cold snap follows more often than not” after an SSW, adding: “We normally expect our weather to come in from the west – with a flow of relatively mild air coming in off the Atlantic.
“When an SSW brings easterly winds this tends to alter our weather patterns slightly, weakening areas of low pressure and moving our jet stream further south.
“This leads to high pressure over the North Atlantic, ‘blocking’ that flow of mild Atlantic air and dragging in cold air from the continent to the east. Exactly how cold it might be depends on the details of where the air comes from.”
The warning of plunging temperatures next week come as parts of the UK were hit by snow flurries amid continuing chilly weather.
The Met Office said the south of Scotland and the Highlands will be worst affected, with possible transport disruption and a “small chance” of power cuts.
Snow could also fall in lower lying areas of northern England on Wednesday afternoon but is expected to be washed away by rain sweeping across the country.
Met Office meteorologist Aidan McGivern said: “It’s turning windy and wet from the west through the morning.
“Already we’ve got outbreaks of rain into western Scotland with winds picking up with gusts reaching 50 to 60mph.
“Temperatures will quickly begin to recover from 0C as the wind strengthens and the cloud pushes in from the west and the rain moves in.
“As that rain pushes into cold air in will fall as snow over the higher ground of northern England Scotland and northern England and, for a time, we could see sleet and snow down to lower levels but it is only temporary, it will soon turn back to rain.
“It will be mild in the south west, 11C or 12C, but under the wind and the rain it’s not going to feel particularly pleasant.
“Meanwhile, just 2C or 3C down the eastern side of Britain and again with the wind and outbreaks of rain and sleet it’s quite a miserable afternoon to come.”