BRITS are set to bask in 22C sun today - before a thunderstorm warning comes into force tomorrow.
Temperatures are forecast to remain high today, with much of the UK enjoying another day of sunshine.
The Met Office predicts that the mercury could reach 22C by 1pm as far afield as York and Southampton - with a peak of 23C in Yeovil, Reading, Swindon, Cambridge and London at 4pm.
But there will be on-off rainfall in Northern Ireland and Wales throughout today - with even a chance of lightning and large hailstones during short, intense downpours.
Elsewhere the fine weather will continue, with the sun burning through the wispy cloud in eastern England and Scotland.
But in rain-soaked Northern Ireland the mercury could sink to just 19C.
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Humidity will make for tossing and turning on Saturday night - ahead of a Met Office yellow warning for heavy rain and thunderstorms on Sunday.
The warning will be in place for the whole of Sunday across England and Wales.
Although some areas will be drenched by long spells of thundery rain, most places will see only showers.
But 30mm of rain could fall in just one hour in some parts of the UK, with 60mm falling across six hours.
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There is also a potential for frequent lightning, strong winds and hail.
Even in the short term there is a great deal of uncertainty about where thunderstorms will develop.
The Met Office said: "Heavy rain and thunderstorms on Sunday will bring a chance of disruption to parts of England and Wales.
"Spray and sudden flooding could lead to difficult driving conditions and some road closures.
"There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.
"Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
"There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.
"There is a small chance that some communities become cut off by flooded roads."
It comes as Brits have been hit by a hosepipe ban - after thousands were left without water for days amid a heatwave.