Parts of Britain are set to be battered by very heavy rain and winds of up to 50mph in an "intense" day of unseasonably bad weather.
The Met Office has yellow warnings of rain and wind in place for the East Midlands, East of England, south-west England, London and south-east England, warning people to "be aware".
MeteoGroup weather forecaster Billy Payne said it is "unusual" to see such significant rainfall in 24 hours.
"We are looking at some very heavy rain across much of southern Britain today and into tonight. It's already arriving into Wales and the South West this morning.
"Across much of southern Britain we could see well over 20-30mm and across the likes of East Anglia, south-east England, even London, there could be perhaps 50-60mm, maybe even more," he said, adding: "It's quite intense."
Mr Payne said the the worst of it, particularly in London, will be overnight, although he did say the capital would be hit with some heavy rain during the day too.
"It's not very often we do see rainfall amounts like that in the space of 24 hours," he said, adding that it is "unusual" to see those sorts of totals, especially across a large area in the South East.
He also said people should expect "quite strong winds" tonight of about 50mph across Kent and East Anglia.
The forecaster said temperatures today will not get much higher than 17C or 18C.
Saturday will be a better day and will be warmer with highs of about 21C, but things will deteriorate again on Sunday, he said.
It is expected to dry up again after the coming unsettled days, and might get a bit a bit warmer, but a heatwave before the end of next week is unlikely.
The Met Office warnings are valid from noon today until 9am on Saturday.