Warnings have been issued as intense lightning and thunderstorms look set to continue into Sunday after the UK was struck by up to 20,000 bolts overnight.
Southern parts experienced the “mother of all thunderstorms” on Saturday evening, weather forecasters said.
The Met Office advised that further torrential rain and thunder are expected on Sunday morning.
Heavy #thunderstorms have brought over an inch of rain to parts of east Wales and the Midlands in just an hour. Further #lightning and torrential showers are expected to continue this morning. Stay #weatherawarepic.twitter.com/KGQ1nNmHmH— Met Office (@metoffice) May 27, 2018
It comes after London Fire Brigade said it had taken more than 500 weather-related calls as the warm and humid bank holiday weather broke down into an “utterly intense” storm.
In Warwickshire, the fire service said five properties were struck by lightning in the early hours of Sunday, while in Dawlish, Devon, a telephone box burst into flames after a BT pole was hit on Saturday evening.
Western Power Distribution said nearly 1,000 properties had been left without power across the Midlands, with the majority of outages down to lightning.
A cluster of 17 flood alerts has been issued for parts of the Thames Valley, while West Midlands and Bedfordshire fire services warned motorists of the risks of driving on flood-hit roads.
Met Office meteorologist Charlie Powell said information suggested there were “somewhere between 15,000 and 20,000 strikes across the UK during the overnight period”.
He explained: “Temperatures overnight did not fall much below 15 or 16 degrees, for the end of May that’s a pretty hot and humid night so everything was primed.
“We had some storms coming in from northern France and some building up in the Channel and they sort of spread out and have been working their way in.
“It looks like there just one huge area of thundery showers that worked across London just before midnight.”
The LFB said it had taken 505 weather-related calls overnight, although the majority were down to flooding and no fires were reported to have been started by lighting strikes.
Torrential rain at Kew Gardens, in south-west London, saw more than half an inch of rain fall in an hour.
Sunday is set to see further disruption from thunder with a Met Office warning of heavy thunderstorms is in place until 6am on Monday, covering much of England and all of Wales.
As it played out in dramatic fashion, skies exploded with light and sound over the capital and across southern England.
BBC weatherman Tomasz Schafernaker tweeted: “Mother of all #thunderstorms now over London. Oh boy! This UTTERLY INSANE. I’ve never seen a storm with such frequent lightning in my life I don’t think. Mostly sheet lightning and not too loud but flashes are spectacular.”
James Brewin captured the moment Big Ben and Westminster were illuminated by a flash of lightning, describing it as “London in daylight at midnight for a split second”.
The lighting storm over London right now is utterly INTENSE pic.twitter.com/yiqQLKng3Z— Andrew Lanxon Hoyle (@Batteryhq) May 26, 2018
Photographer and journalist Andrew Lanxon Hoyle shared an image of the Suleymaniye Mosque in Dalston, east London, lit from behind by a brilliant fork of lightning, tweeting: “The lightning storm over London right now is utterly INTENSE.”
Pamelasaurusrex shared a photo on Instagram of two people running for shelter outside King’s Cross Station as a lightning bolt arced across the sky over nearby St Pancras.
Samuel Wilkinson captured the split-second lightning shot toward the earth with The Shard skyscraper below, while the RNLI at Tower Bridge shared a photo of the view over the South Bank as the sky lit up.