The weather in the UK this weekend is set to be warmer after an “especially cold” Thursday night.
Temperatures overnight dropped below zero degrees Celsius in all four nations, with a low of -2.7C (27F) recorded in Topcliffe, North Yorkshire.
There was also a widespread frost amid cold Arctic air, the Met Office said.
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It is the earliest the south of Wales has seen frost in September since 2019, according to the weather agency.
With clear skies across England and Wales on Friday night, there is expected to be another frost, particularly in the South.
But the unseasonal cold weather will give way to a warmer weekend with many areas set to be “fine and dry” and temperatures reaching the high teens or even 20C (68F).
Sky weather producer Joanna Robinson said: “A northerly flow brought a chilly few days, and it was especially cold on Thursday night, with temperatures dropping below freezing in places.
“Friday night won’t be quite as cold, but clear skies across England and Wales will allow another rural ground frost to develop, especially in the South.”
She said the weekend will be “milder as the northerly flow gets cut off”, with winds coming from the South West instead. That will help temperatures return to near average.
Looking ahead, she added: “Temperatures will continue to rise next week, reaching the high teens in the North and low 20s Celsius in the South by Tuesday. That’s a few degrees above the September average.
“There’ll be a lot of dry weather around too, with some pleasant sunshine, but the North will see wind and rain on Saturday.”
Robinson also said there is likely to be heavy rain and severe thunderstorms over the next few days in parts of central Europe, with rare red weather warnings issued.
She said there could be “extreme rainfall” with up to 300mm (nine inches) – and potentially double the September average – in some areas, with southern Poland, Austria, the Czech Republic and western Hungary and Slovakia most at risk.
She added: “Significant – once in a century – flooding is feared and, along with the heavy rain, over a metre of snow is possible for parts of the Alps.”
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Speaking about the UK, Met Office chief meteorologist Jason Kelly: “The cold Arctic air we have been experiencing will be replaced with warmer westerlies over the weekend.
“High pressure will bring fine weather to the South, but there is an area of low pressure to the North West, which will push some weather fronts across Scotland and Northern Ireland, bringing rain and thicker cloud.
“It will also be windy across northern Scotland, especially on Saturday.”
Sunday will see another change as cloud and patchy rain hit parts of northern England and Wales, as the warm weather front moves southeastwards.
It will be dry in the South but the North could see some showers.
The warmer temperatures are expected to stay around next week, with the weather likely to be dry for many.
Deputy chief meteorologist David Oliver said: “If any rain develops it is expected to be confined to the extreme northwest of Scotland on Monday and Tuesday.”