The Met Office has issued warnings for thunderstorms, heavy rain and flooding as the May bank holiday ends in a washout.
Lightning storms are expected to round off a mixed weekend of weather which saw the North have long bright sunny spells and temperatures as high as 21C.
Forecasters warned that “spray and sudden flooding could lead to difficult driving conditions”, on ‘mayhem Monday’ which expects to see millions of drivers take to the roads.
The South started with sunny spells before heavy showers and thunderstorms are expected to move in through the afternoon.
Forecasters have put two yellow alerts for thunder, covering the south east of England, the north west and parts of southern Scotland.
Thunderstorms and heavy downpours are likely to break out across Glasgow, Manchester, all the way down to central Wales between 1pm and 9pm.
Although not all places will catch these storms and downpours, where they do occur 20 to 40 mm of rain may fall in an hour, the forecaster has warned.
In London, heavy downpours began at 8am and are set to last until midnight – with the Met Office forecasting around 14 hours of rain.
They added it will be drier for Northern Ireland and western Scotland.
Another yellow thunder warning is in place in the south east across Kent, Sussex Surrey and south London.
In these areas, 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 also a chance of fast-flowing or deep floodwater causing danger to life.
Greg Dewhurst, a meteorologist at the Met Office, said: “Overall, it will be a mix of sunny spells and showers across the country.
“Anywhere could catch some rain so people should be prepared for that. For people looking to get away, there will be some sunshine and warm spells. And if you manage to avoid showers, then it will be nice in the sun.”
It came as more than 2.5 million drivers face being stuck in motorway traffic as the bank holiday draws to a close.
The RAC warned drivers to avoid making journeys from 10am to 3pm because the highways like the M5 will be at their busiest.
A severe flood warning is in place across the Scrasebridge and West Common Streams, which is described as “high and rising” by the Environment Agency.
45 flood alerts where flooding is possible remain in place across the South.
Tuesday will begin with cloudy start, but sunny spells will develop for most through the day with a few showers forming in the south in the afternoon.
By Wednesday the Met Office predicts the weather will be largely fine and dry with cloud and some “rather worm sunshine”. The rain clouds are expected to move on to Northern Ireland and northern Scotland.
Last Wednesday the Met Office recorded 4,840 lightning strikes across France and southern Britain overnight.
Heavy rain and thunderstorms trampled their way across southern England and Wales.
Two buildings in Sussex were damaged by lightning strikes, according to West Sussex Fire & Rescue.
A care home in Elmer was struck with damage to its roof while a university building in Chichester sustained damage to its roof and power system.
Source Agencies