The Met Office has issued a severe weather warning for parts of England and Wales for heavy rain and possible flash flooding.
Rain is sweeping across East Anglia, London and the south east, Yorks and Humber, the Midlands, and eastern Wales, with up to 8cm (3in) predicted.
The rain is forecast to fall quickly onto already saturated ground.
The BBC Weather Centre said it would be followed by gale-force winds and gusts reaching more than 60 miles per hour.
The winds would especially affect more exposed parts of Kent, Norfolk and Lincolnshire.
The Met Office said this could mean potential disruption to the morning rush hour and to outdoor events in England.
It added that slow moving heavy rain was also expected in western Scotland and Northern Ireland overnight.
'Branches on roads'In England, the rain would be accompanied by strengthening winds along southern and eastern coasts.
A BBC weather centre spokeswoman: "There is a risk of local flooding, and with the wind there is also the risk of disruption due to loose branches and debris on the roads."
She added that the heavy weather was more typical of autumn than summer, but that the worst of it was likely to have passed by 0900 BST on Monday.
The most intense downpours are expected in the early hours across Somerset, Hampshire, Essex and Lincolnshire.