The Environment Agency is urging people along the south coast of England between Dorset and Kent, to be vigilant and prepared for the risk of flash flooding.
A line of thunderstorms is expected to bring 15-25mm of rain in an hour in some places, with the potential for up to 50mm (a month’s worth of rain) in just a few hours.
There is also a risk of flooding from rising groundwater across parts of Wiltshire, Somerset and West Dorset, including Salisbury Plain.
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Monday night's forecast for the east of the region
Monday night's forecast for the west of the region