Storms across eastern parts of the UK were predicted to dampen temperatures on Friday as weather forecasters warned of “danger to life”.
Officials issued an amber warning for thunderstorms in the East Midlands and East of England valid between 2pm and 8pm on Friday.
They said fast-flowing floodwaters would be hazardous and that damage to property from lightning strikes, hail and strong winds was likely.
And as thermometers rose:
- Eurotunnel cancelled thousands of tickets while power outages elsewhere on the railways caused major disruption;
- Police forces have been called following concerns for people’s welfare at rivers and a lake;
- Firefighters rushed to extinguish a blaze after lightning struck a house in Nottinghamshire;
- Drivers were warned to expect localised floods and spray and surface water on roads as thunderstorms swept in.
Thunder and rain overnight in the north east of England and the east of Scotland has lowered the chances of a new heat record being set, the BBC’s Weather Centre said.
Forecasters at the Met Office predicted on Thursday that wilting Britons could be forced to contend with temperatures higher than the 38.5C seen in Kent in 2003.
Air moving in from the Atlantic could see some areas of the UK see a 10C drop in temperatures overnight into Saturday.
Thursday saw the hottest day of the year so far, with temperatures of 35C recorded at Heathrow.
A mix of toxic air, extreme highs, emissions from the continent and a lack of cloud cover caused a “high” air pollution alert to be issued for London.
Authorities said the heatwave was causing “winter conditions” in parts of the NHS, with many overworked nurses said to be dizzy and exhausted.
Fire brigades also called for a ban on BBQs in parks and drivers were urged not to throw rubbish following a string of grassland fires in recent weeks.
Eurotunnel took the “unprecedented decision” to stop passengers from travelling on Friday if they were due to return on the same day or on Saturday in a bid to ease long queues.
Airports were separately braced for the busiest day of the year as millions jet off abroad, with fears sudden downpours and flooding could affect runways.
And rail operator LNER advised passengers to consider cancelling travel as lightening caused power problems at York.
Meanwhile, Chessington World of Adventures theme park in Surrey was forced to close after a burst pipe caused a water shortage.
Warwickshire Police officers at the Bishops Bowl Lakes area retrieved a body following reports a 17-year-old was missing in open water.
Essex Police said a search for a teenager last seen in water near Clacton Pier on Thursday evening had resumed on Friday morning.
Elsewhere the musician James Arthur cancelled an open air show in Scarborough because of lightning strikes in the area, promoters said.
Going into Friday night more showers will come into parts of Wales, south west England and northern Ireland in a sign of things to come for the weekend, Deakin added.
Most places will see temperatures closer to average for the time of year, around the high teens to low 20s, with the chance of showers and strong breezes, Deakin said.
Some areas will see a more than 10C drop between Friday and Saturday, he added.
He went on: “Weather fronts are trying to come in from the Atlantic and eventually they will do so.
“And that has the impact of ousting the really hot and humid air .. it turns cooler for the weekend, fresher, more comfortable at night.”
Firefighters are battling a house-blaze after it was struck by lightning on Friday morning.
The fire in Langold, Notts, erupted amid reports of lightning strikes across the East Midlands this morning.
It comes as scientists warned that climate change is making such heat extremes more likely, and the report comes as northern Europe swelters in a prolonged heatwave.
With reporting from the Press Association.