TORRENTIAL rain and heavy flooding are set to swamp the country tonight as the mini heatwave comes to an abrupt end.
The Met Office extended the yellow weather warning across England and Wales as gloomy clouds roll in.
Brits are bracing for a downpour just days after festivalgoers at Glastonbury partied in scorching 28C sunshine.
Forecasters warned the wet weather could cause travel disruption after expanding the yellow warning westwards and northwards.
Up to 40mm of rain is expected to fall in as little as one hour in areas where thunderstorms let rip – rising to 60mm over a two or three-hour period.
But there exact locations “will be hard to pinpoint”, while frequent lightning, gusty winds and hail may also hit some spots.
Revellers at Glasto will face a washout, while roads, homes and businesses could flood.
The Met said: “There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.
“There is a small chance of fast flowing or deep floodwater causing danger to life.”
Meteorologists also cautioned Brits there is a slight chance that power cuts could occur.
Festivalgoers are fearing Thursday could end in a mud bath, with those enjoying the event being informed they may need to “shelter if they can”.
There’s even a flood warning in place that could spark misery for tens of thousands of campers amid fears more than two inches of rain could fall in just a few hours.
Wales could also see some of the worst weather.
The warning covers almost a full day – from 10am until midnight.
And tomorrow won’t be much more cheerful.
The Met Office’s deputy chief forecaster Daniel Rudman said: “From Friday onwards, the weather will become more unsettled.
“There is a risk of heavy showers and thunderstorms in the Glastonbury area on both Friday and Saturday, although these should be quick moving.
“Some surface water might accumulate at times from the heaviest showers.
“Temperatures will start to dip as we go through the end of the week, returning to near normal for the time of year, with highs likely around 18-20C.”
His colleague Helen Caughey urged Glasto fans to pack “both sunhats and raincoats”.
Hail and wind could also lash Worthy Farm in the days to come.
The Met Office has warned there’s a “small chance” some places in the country will be “cut off” by floods.
Netweather forecaster Jo Farrow said the tempest could be severe.
“It has the ingredients for torrential downpours, thunderstorms – home-grown and imported in the plume – sudden gusty winds and hail, with flash flooding from the heavy rain as it has been dry recently,” she said.
Meanwhile, those heading to Somerset today for the party will also face another challenge after rail strikes take hold yet again.
Many services have been halted completely, while half of services to Castle Cary for the festival won’t run.