UK to experience '20C swing' as spring sunshine accompanied by sub-zero temperatures this weekend
The dramatic dip in temperatures will see the mercury plummet into Sunday
The UK is bracing for a dramatic swing in temperatures this weekend as spring sunshine is set to be replaced by sub-zero temperatures.
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The joy is set to be short-lived for sun worshipers as the UK experiences a '20C swing' - with highs of 17C replaced by temperatures as low as -2C in south London overnight.
The drastic swing comes as the Met Office warns of patchy rain moving southeastwards across the UK on Sunday.
Some sunshine is expected to develop across southern England despite a foggy start, with colder weather arriving in the northwest, alongside some blustery showers into the afternoon.
Clear skies for England and Wales will bring a dip in temperatures, with parts of England set to experience "patchy frost" overnight with"some low cloud and fog developing".
Temperature swings of 20C remain relatively rare, with the drastic dip described by experts as a natural phenomenon.
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Similar swings have been seen across parts of Northern Ireland in recent days, with the mercury dipping to -3C in Belfast overnight on Friday, before rising to 16C during the day on Saturday.
It comes as temperatures across parts of Scotland hit lows of -4C on Friday.
Becky Mitchell, a senior meteorologist with the Met Office, said the swings were caused by the body of air above the UK remaining relatively cold and the ground yet to absorb and retain heat from the sun.
“When we have sunny weather and clear skies, we lose the heat from the ground very quickly overnight, raising the potential for temperatures to fall quite low,” she said.
👀 Watch this satellite loop from this morning to see how the fog shrinks as the March sunshine burns it away 🌤️🌫️
— Met Office (@metoffice) March 21, 2026
Have you been enjoying the fine weather so far this weekend? pic.twitter.com/ct1F3KwQJU
“By day the sun has quite a bit of strength at this time so it doesn’t take too much for those temperatures to rise,” she added, creating a “spring swing” in temperatures.
The warm days and cooler nights come as conditions remain dry across the UK following record rainfall in January.
A fine afternoon for the vast majority with plenty of sunshine, albeit a little hazy in places. Generally not as warm as recently but feeling pleasant in the sunshine and light winds 🌤️
— Met Office (@metoffice) March 21, 2026
Cloudier and breezier in northern Scotland with some light rain in places 🌧️ pic.twitter.com/E5be6J4Htm
Met Office Chief Forecaster, Steve Willington, said: “While the early part of the period brings warm sunshine for many, it’s not unusual to see colder spells and even some wintry showers in March.
As we head into next week, a shift to a cooler north‑westerly flow will bring a drop in temperature and more unsettled weather, including some hill snow in the north and brisk winds at times.
"This pattern is entirely typical for the time of year.”