Hundreds of flights at London’s Heathrow and Gatwick airports were delayed or cancelled on Saturday after severe thunderstorms swept across southern England, with disruption expected to continue into Sunday.

According to flight tracking service FlightAware, more than 900 arriving and departing flights at the UK’s two busiest airports experienced delays of up to 11 hours, while dozens of services were cancelled.

Heathrow Airport recorded more than 474 delayed departures and arrivals, while a further 439 flights were delayed at Gatwick Airport as adverse weather affected operations across the region.

The UK’s air traffic control provider, NATS, warned that passengers should continue to expect disruption into Sunday as thunderstorms and operational constraints impact flight schedules. Airlines were forced to delay, reroute or cancel services to maintain safe separation between aircraft during periods of intense storm activity.

The storms developed overnight following a record-breaking heatwave that affected large parts of the United Kingdom, with the sudden change in weather creating hazardous flying conditions across southern England.

Passengers travelling through Heathrow and Gatwick have been advised to check the latest status of their flights with their airlines before leaving for the airport, as recovery from the disruption is expected to continue throughout the weekend.