SCREENGRAB/BBC
Flights at London's Heathrow and Gatwick airports have been delayed for up to six hours as the heatwave turns to thunderstorms.
More than 600 flights have been delayed in and out of the two travel hubs so far on Saturday and dozens cancelled, many due to the stormy weather. The UK's air traffic control service said delays were expected to continue for the rest of the day.
Some passengers have taken to social media to express their frustration, with one saying her daughter had been stuck on an Easyjet plane at Gatwick for four hours before it was cancelled.
Gatwick told BBC News that temporary air traffic control restrictions had been put in place, while Easyjet apologised for the disruption.
At least 367 flights arriving at or departing from Heathrow have been delayed so far on Saturday, according to tracker FlightAware, and 352 in and out of Gatwick.
Europe-wide aviation agency Eurocontrol says Heathrow and Gatwick are the only two UK airports currently facing "heavy" delays related to the thunderstorm.
Delays to affected flights vary, but Gatwick's live departure board shows an Easyjet flight to Antalya delayed from 11:50 BST to 18:00.
Other flights have been delayed by four hours, with airlines including British Airways at Heathrow affected.
Eurocontrol shows the most severe air traffic control delays in airspace between south-east England and north-western Europe, where the storm clouds currently are.
However, flights travelling on flight paths outside of the storm area are still leaving and arriving on time.
Passengers grounded for hours
NATS, the UK's air traffic control service, said "weather disruption was expected to continue through the rest of the day" after "forecasted severe weather across the south east of England".
Gatwick confirmed some flights had been delayed and cancelled on Saturday "due to ongoing thunderstorms" and temporary air traffic restrictions.
Heathrow is advising passengers to check the status of their flight with airlines before travelling.
Passenger Adam Joseph, 29, told BBC News that he had been stranded at Venice airport in Italy without air conditioning because his flight to Gatwick had been delayed by four hours and counting.
He was due to depart Venice at 12:30 local time but said the plane had not yet left London on its outbound leg.
"We could've stayed at the hotel for another three to four hours," Joseph said.
"We are also being told that even in the event of a four-hour-plus delay, because of an air traffic control restriction we will not be entitled to compensation."
He added: "I've had to give up my chair to a family with a pregnant mother.
"People are very angry... we have had no communication from [BA] whatsoever."
British Airways said in a statement: "Like other airlines, we've had to make some adjustments to our schedule today due to air traffic control restrictions caused by adverse weather conditions affecting parts of UK airspace."
The airline apologised for the inconvenience and said it was working to get journeys back on track, stressing that the vast majority of customers would be unaffected.
Meanwhile, one woman wrote to Easyjet on X on Saturday morning: "My daughter has been sat on a plane at Gatwick for 4 hours and now you've cancelled the flight. She's on an Easyjet holiday. What should she do?"
Easyjet said that, with thunderstorms restricting the number of arrivals and departures, it has had to "pre-emptively cancel some flights to and from Gatwick in advance".
"We are doing all possible to minimise the impact of the weather disruption for our customers and are notifying passengers in advance with their options to rebook or receive a refund as well as hotel accommodation and meals where required," a spokesman said.
Parts of eastern and south-eastern England remain very hot this weekend, with a Met Office amber warning for extreme heat in place until 09:00 BST on Sunday - but isolated thunderstorms are affecting parts of the UK too.
The thunderstorm to the south of the UK is forecast to worsen throughout Saturday afternoon.
