Floods have lashed parts of the UK, leaving some homes, businesses and streets under water.
The heavy slow-moving showers had led the Met Office to issue an amber thunderstorm warning covering most of the south east of England, including parts of London, on Wednesday.
A yellow thunderstorm warning was also in place for the east of England, London and the south east plus the south west.
A warning was also issued for thunderstorm across parts of Kent and Medway on Thursday.
Gatwick Airport warned the weather conditions could cause flight delays.
Gatwick Airport tweeted: “Air traffic control restrictions are currently in place across the South of England and parts of Europe due to poor weather conditions.
“This will unfortunately cause delays and cancellations to some flights today.”
Flooding also hit the busy central London Victoria Station, forcing some shops and platforms 7 and 8 to close for a period in the afternoon.
A Network Rail spokesman said: “Not long after 3pm this afternoon, station colleagues at London Victoria noticed flooding at the main entrance due to heavy rainfall, with large volumes of water running down the slope leading towards the eastern concourse.
“Some retail units and platforms had to be closed.”
Southeastern Railway introduced “precautionary speed restrictions” on its Hastings line, and between Tonbridge and Ashford International as a temporarily measure.
As the evening rush hour began, London mayor Sadiq Khan said: “Parts of London and our transport network are currently experiencing disruption due to thunderstorms and flash flooding.”
The Met Office amber warning said: “Fast flowing or deep floodwater is likely, causing danger to life.”
Flooding is likely to affect homes and businesses “quickly”, as 30mm to 50mm of rain could fall in just an hour, while a few places may see more than 100mm in a few hours.
Forecasters say this could lead to train and bus cancellations amid difficult driving conditions, power cuts and communities becoming cut off from roads.
Lightning, hail and strong winds could also lash areas included in the warning, which spreads across Suffolk, Kent, Surrey and West Sussex.
The sudden downpours hit as Thames Water, which supplies 15 million people, confirmed it is putting a hosepipe ban in place next week, saying water levels in its reservoirs were “much lower than usual”.
The gym in the Houses of Parliament was also flooded out.
Town hall officials in Hackney warned residents that “severe flooding” meant they should “avoid” Stoke Newington in the east London borough and it was working to clear drains and hand out sandbags.
Heavy downpours also left “large pools of water in several locations” in Islington and Finsbury Park, north London, the council said .
Wednesday was the fourth day in a row of thunderstorm warnings in the UK.
Nottinghamshire County Council said that at least 30 homes and business premises in its region were hit and an eight-foot-wide sinkhole had been reported to have appeared in the Matalan car park.
Worksop Leisure Centre was put on standby as a rest centre in case properties needed to be evacuated and a tree was reported to have fallen in Carlton Road, according to the council.
Doncaster and Bassetlaw Teaching Hospitals NHS Foundation Trust said it was carrying out “a drying out job” and asked people to ensure the emergency department is “used appropriately”.
A spokesman said this was needed as a heavy downpour had left standing water that had got into some of the buildings in Bassetlaw Hospital.
Stagecoach East Midlands, which serves Hull, Lincolnshire and North Notts, told customers that all of its services had been operating “to the best of our ability” but flooding had caused disruption across the whole Worksop network.
The Environment Agency’s flood duty manager Neil Davies said: “We urge people not to drive though flood water – it is often deeper than it looks and just 30cm of flowing water is enough to float your car.”