The Environment Agency has issued more than 20 flood alerts for north England, the Midlands, the South East and Wales as heavy rain is set to lash the country.
The Met Office has also issued a number of severe weather warnings, for the Central, Tayside and Fife, London and the South East, south-west Scotland, Lothian Borders, the South West, Strathclyde and Wales.
It warned that heavy rain of up to 30mm (1.2in) will fall over high ground in Scotland during the morning, with thunderstorms and gusts of up to 60mph along the south coast of England.
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The decision was made after two Russian athletes failed drugs tests at the PyeongChang Games.
Sunday will be dry and largely sunny, although there will be some patchy cloud, mainly across eastern Scotland and eastern England.