UK heatwave: Final day of 'extreme' heat with thunder on way - BBC News
Temperatures have exceeded 30C in much of England and Wales - but rain is forecast.
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Much of the UK has been experiencing another day of high temperatures - but the spell of extreme hot weather is coming to an end with thunderstorms.

Scotland and Northern Ireland had rain and lower temperatures on Sunday, and rain started falling in parts of north-west England late on Sunday.

Other parts of England and Wales will see rain on Monday.

Experts have warned a lengthy period of rain would be needed to end the drought declared in parts of England on Friday.

A lot of land has been left parched and hard by the heat, so rain is likely to hit the ground and run off - as it would on concrete - which could lead to flash flooding.

A Met Office extreme heat warning has been in place for a large part of England and Wales for four days - making it the lengthiest alert since the system was introduced last year.

It has not been as high as July's heatwave - when recorded temperatures in the UK topped 40C for the first time - but the extreme heat has lasted longer.

Temperatures reached as high as 34.1C in Charlwood in Surrey on Sunday - while Edinburgh had thunder and heavy rain.

Dan Stroud, a meteorologist at the Met Office, said: "We've had high pressure dominating, now we're having low pressure dominate, so the air is becoming more unstable.

"As we've had some very high ground temperatures, it doesn't actually take too much for the air to become even more unstable and for thundery showers to develop quickly."

Lincolnshire Police confirmed a teenage boy died on Saturday in the sea at Skegness as temperatures prompted many people to flock to the beaches.

The hot weather has also led to wildfires around England, from the North York Moors National Park to Dorset on the south coast.

Mark Hardingham, from the National Fire Chiefs' Council, said: "We've had 745 wildfires this year and that's gone up by 150 in just the last week. Last year we had 247 across the whole of the 12 months."

There are hundreds of other less serious fires in grassland every day, he said.

Two men, both 44 and from Boston in Lincolnshire, were arrested on suspicion of arson and criminal damage after a fire broke out in Norfolk, the county's police forced said.

Emergency services had been called to Bawsey Country Park, near King's Lynn, on Sunday at about 11.40am, after a disposable barbecue in a woodland caused a small fire.

Norfolk Constabulary said two men, both 44 and from Boston in Lincolnshire, had been arrested on suspicion of arson and criminal damage and taken to King's Lynn for questioning.

Extreme heat warnings are based on the impacts of the weather conditions, rather than when specific temperatures are reached, the Met Office said.

This means different conditions in different areas of the UK may trigger an extreme heat warning.

The heat warning only covered England and Wales but Northern Ireland experienced its warmest August day for nearly 20 years on Thursday.

Meanwhile, temperatures were high enough in Scotland to cause a wildfire in West Lothian that has burned for several days.

And farmers in Fife have warned a newly-imposed ban on extracting water from the River Eden could lead to complete failure of some crops, with the National Farmers' Union calling the move "devastating for agriculture".

But in Scotland and Northern Ireland, a yellow warning for thunderstorms came into effect on Sunday morning, due to last until the end of Monday.

Customers at a Tesco supermarket in Inverness had to be evacuated on Sunday after water poured in through the ceiling.

Rain fell in parts of north-west England on Sunday evening too, including Lancaster and Kirkby Lonsdale, ahead of the yellow thunderstorm warning spreading to England and Wales across Monday and Tuesday.

South-west and south-east England face a third day of yellow warnings on Wednesday when northern areas are expected to be drier.

The hot weather has parched the grass in Greenwich Park, south-east London

A boat sits in the dried up Huddersfield narrow canal in West Yorkshire

An official drought was declared for eight areas of England on Friday. The move is expected to trigger stricter controls on water use and five water companies have already announced restrictions, including hosepipe bans.

John Curtin, executive director of local operations for the Environment Agency, told the BBC "this is not a normal summer" and warned lack of water would be an issue for several months.

"We'll need probably average or slightly above average rainfall this autumn into this winter for us to not be in a drought next year," he said.

The agency has said there is enough water for public supply but has urged everyone to think about their water use.