In addition, there is a possibility that lightning strikes and strong winds will cause damage to some buildings.
The storms on Friday could even bring hail, while in some areas there could be up to 50mm of rain falling in an hour.
The Met Office predicts flooding may occur quickly due to rainfall
Difficult driving conditions could follow, due to sudden flooding and spray from other cars, while other transport links such as rail services may also be disrupted.
The Met Office has also warned there is a chance of power cuts that will affect homes and businesses up and down the nation.
“Heavy showers and thunderstorms are likely to break out on Friday afternoon and evening. Many places will miss the storms, but where they do occur, torrential downpours could bring 30-50mm rain in an hour, with hail and lightning,” the Met Office said.
There are two yellow thunderstorm warnings issued by the Met Office.
A lighting strike map shows heavy hits across Wales particularly
The first has been in place since 16:00 on Thursday and is in place across the whole of the UK’s west and south coast, including all of Northern Ireland. This will expire on Friday morning at 09:00.
The second one will run from midday on Friday until 09:00 in the morning on Saturday, as the storm moves from the west coast and begins to hit the central and eastern areas.
For this second warning, the far south-east of England is exempt, the Met Office said.
Met Office meteorologist Craig Snell told PA news agency: “Not everyone will see a storm, but if you catch one, you will certainly know about it”.
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The storm will initially have passed across the west coast of the UK and start hitting the east as Friday goes on.
The storm will slowly head in a northeast direction through Friday, and will probably clear northeast areas of Scotland by Saturday morning.
The storms will come as a stark contrast to the wall-to-wall sunshine and heat experienced in much of the UK this week; Thursday was the country’s hottest day so far.
London’s Heathrow Airport, for example, clocked a high of 33.4 degrees.
While in Scotland and Wales the temperatures both tipped over the 30 degree line.
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The weather is likely to get breezy into next week.
While Friday will certainly see a change in terms of sunshine, the temperature will remain warm – perhaps stiflingly so, due to the humidity.
But temperatures will begin to cool on Saturday in the wake of the storm, which might leave a mixture of rainy and sunny spells as it goes.
Through Sunday to Tuesday, expect the weather to turn windier and fresher, though for many there will be longer spells of rain particularly in the north and northwestern areas of the country.
The hot weather this week has led to a major incident being declared in Bournemouth on the south coast, where tens of thousands of people flocked to go to the beach despite warnings to stay away.
Temperatures will remain high for Friday before lowering on Saturday
The local BCP council said it had to put in place an emergency response in order to tackle a range of problems such as beach overcrowding, traffic gridlock, and even violence.
The Guardian reports that litter collection teams were escorted by security guards.
On TalkRadio, Health Secretary Matt Hancock said that while people had had “a pretty tough lockdown”, the government would close beaches if it felt it was necessary to get Britons to observe social distancing rules.
The storm should head northeastwards before dissipating on Saturday.
Meanwhile, BCP council leader Vikki Slade said the council was “absolutely appalled at the scenes witnessed on our beaches”.
She added that the council is “not in a position to welcome visitors in these numbers now” and asked people not to visit the area.