Thunderstorms and heavy rain will batter most of the UK Saturday and Sunday as with warnings for floods across the country.
Yellow weather warnings have been extended for the North East of England, Midlands and most of Scotland and remain for both today and Sunday.
North West of England and parts of Wales and Northern Ireland will also see stormy weather throughout the dismal weekend.
Met Office says: "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.
"Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services. Spray and sudden flooding could lead to difficult driving conditions and some road closures.
"There is a small chance that some communities become cut off by flooded roads. There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost."
Initially, the weather warning concerned most of central England but forecasters have expanded it significantly.
Up to 80mm of rain could fall in just a few hours today, it is now understood.
The most rainfall is expected in South West England, notably in and around Bath, Bristol and down into Devon.
The Met Office added: "Heavy, perhaps thundery, downpours may become concentrated into a narrow corridor of persistent heavy rain on Saturday afternoon and evening.
"Where this occurs, 20-30 mm rain may fall in an hour with 40-50 mm of rain in 3 or 4 hours, and a small chance of up to 80 mm in a few places. This brings a risk of localised flooding and disruption, whilst locations either side of this shower band may see very little rain."
Elsewhere, around 40mm of rain in three hours is likely during the thunderstorms.
The Met Office added: "Many places will see a short period of heavy rain whilst some may see a more prolonged period of rain along with some intense bursts, with lightning and hail. Under the heavier rain some sites could see 30-40 mm rain falling in a few hours."
The forecast looks set to ruin football fans' plans to watch the Euro 2020 match outdoors tonight.
The weather will threaten Wimbledon, which began in the sunshine at the start of the week.
Sports fans have been meeting in beer gardens and town squares to enjoy the games but opportunities for these plans look unlikely today.
In Exeter, in the region where the heaviest rain is expected, the average precipitation level for the whole of July is just 46mm. The city could see twice its average rainfall in one day.
And Newcastle, subject to the thunderstorm warning, usually sees 54mm of rainfall in the whole of July but nearly 80% of that could lash down today alone.
However, some parts of southern England and Wales may dodge the downpours, particularly on Sunday.
The yellow weather warning doesn't cover Essex and Kent on Sunday.
