Snowstorms are due to affect large parts of England on Thursday, while sleet and rain batter much of the rest of the UK.
The Met Office has issued an amber warning for “strong winds bringing blizzard conditions” and up to 16in (40cm) of snow for an area stretching from Stoke-on-Trent to Durham.
The alert, which warns of likely “significant disruption” to transport, power lines and phone network coverage, lasts for 21 hours from 3pm on Thursday and covers major cities including Liverpool, Sheffield, Bradford and Leeds.
Daytime temperatures in the low single figures and sub-zero temperatures overnight are predicted for much of the UK, with slightly warmer conditions in the south.
The Environment Agency has issued five alerts for locations on the south coast of England, and for residents between Putney Bridge and Teddington Weir along the River Thames in London, where flooding is “possible”.
The Met Office has said an Arctic air mass from the north meeting mild air from the south is causing the turbulent weather over central areas.