Weather forecasters have warned that heavy rain, thunderstorms and hail could bring flooding to parts of Britain.
The Met Office has issued a severe warning of heavy rain for London and the South East, South West England, the East, Yorkshire, the Midlands, Wales and Grampian.
Up to 1.5 inches of rain could fall within an hour in some areas, forecasters warned.
Met Office forecaster Emma Sharples told the Daily Mail: "Heavy rain has moved up from the south overnight and by 9am it will be over the north of England and Wales – though there will still be thundery showers over the south as well.
"It has been caused by weather fronts that have started to move in from the south and the west, which have combined with low pressure and the warm temperatures over the continent."
The next few days are set to be unsettled, with more showers predicted.
Speaking to AOL Travel, chief forecaster at The Weather Channel, Leon Brown, said: "Saturday looks a rather wet day for Central to Northern England. Some heavy rain is expected early in the day moving from East Anglia and the Midlands to North Wales and the North of England, followed by a lot of heavy showers with local downpours, hail and thunder. 20 to 25mm of rainfall is likely quite widely but it will be drier over Scotland with just a few showers."
There's better news for Bank Holiday Monday with a fine and quite sunny start for England and Wales. Mr Brown says that scattered showers will develop over South Wales to South West England by the afternoon, with the threat of some rain late in the day reaching the South East. But it will be a mild 17 to 20C.
For the rest of next week, there is likely to be more unsettled weather across the South as another area of low pressure develops, while the best of the weather is expected over the North West of Britain with shelter from the prevailing East to North East flow. Leon adds: "Temperatures will be near average and perhaps a little above over the West to North West of the UK until mid-week, in the 18 to 21C range."
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