The UK is likely to experience “several days of cold, potentially disruptive weather next week” including possible rain, sleet and snow, the Met Office has said.
Forecasters said it was too early to pinpoint exactly where the wintry weather might hit, with computer models showing a range of different scenarios.
But there is confidence that much of the UK will turn cold.
Tom Morgan, a meteorologist at the Met Office, said: “The really cold air is likely to arrive next week and there will be some snow in parts of the UK.
“There’ll be a messy mixture of rain, sleet and snow.
“And also quite windy conditions, probably on Monday, in parts of the UK, but all areas will turn cold with wintry showers probably by Wednesday.”
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Mr Morgan said it was “fairly unusual” for such wintry conditions to be forecast in the south for the time of year, and attributed the “cold spell” next week to a change in the positioning of the jet stream.
“At this point, anywhere in the UK has a chance of seeing snow and ice and frost by night, particularly from mid-week onwards,” he said.
Meanwhile, meteorologist Alex Deakin said next week would see “colder air spreading across the UK”.
“A weather system is developing just to the west of the UK bringing in moisture”, he said, and it’s how that “interacts with the colder air that’s giving us the question marks about how much snow we’ll see”.
“As we go into next week we are more likely to see these weather systems tracking into parts of the south [of England], and the colder air spreading across the UK.”
He added there is some uncertainty about the detail, but warned that “precipitation, sleet and some hill snow is possible”.
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During the start of November, a period of high pressure locked much of the country in a cycle of fog, drizzle and low cloud.
A number of weather stations across England and east Wales recorded no sunshine at all in the first eight days of this month.
Gloomy weather produced above-average temperatures in many parts, but since then it has become cooler.