Warnings are in place for flooding and thunderstorms across large parts of the UK, with stormy weather set to last until early evening.
It follows the hottest day of the year on Friday, which saw a high of 29.4C (84.9F) in Santon Downham in Suffolk.
The Met Office has issued an amber weather warning until 6pm across the South West, North East and North of England, Wales and much of Scotland.
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They said there had been over 30,000 lightning strikes during the night, with the “vast majority” over the sea.
The Met Office has warned some areas could see 30-50mm of rain in a few hours, while a few locations could reach up to 80mm.
At the same time, strong wind gusts and hail accompanying the storms could potentially bring road flooding, difficult driving conditions, power cuts and flooding of homes and businesses.
The Environment Agency urged the public not to drive through flood water, reminding drivers that “just 30cm of flowing water is enough to move your car.”
A further yellow warning is in force in the eastern half of Northern Ireland from 6am to 6pm on Saturday, while a similar warning has been in place across the South East of England overnight following an amber alert on Friday.
Kent experienced heavy rainfall overnight, with flooded roads in parts of Dover, while a fire in a residential building in St Leonards-on-Sea on Friday night was likely caused by a lightning strike, the East Sussex Fire and Rescue Service say.
Devon received five flood warnings overnight by the Environment Agency, alongside 46 flood alerts in the South West, South East and Midlands.
A further six flood alerts have been put in place by Natural Resources Wales in South Wales.
National Rail said a landslip had stopped all services between Exeter St Davids and Okehampton, with the weather conditions meaning it is not safe for engineers to reach the site. Disruption is expected until around 1pm.
Other rail operators also warned customers to check for updates on services on Saturday morning.
Heathrow Airport apologised to passengers late on Friday night for flights delayed by “adverse weather conditions”.
Sky News weather producer Steff Gaulter said: “The most active thunderstorms are over parts of Wales, Northern Ireland, Northern England and Scotland, and some are still bringing localised downpours and strong winds.
“The storms will continue northwards, becoming largely confined to Northern Ireland and Scotland by the afternoon. Elsewhere will see a mixture of sunshine and showers, with the showers tending to ease during the day.
“Then from tomorrow an area of high pressure will start to stretch towards us, and the weather next week is looking far calmer and quieter.”
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Despite the risk of heavy showers and thunderstorms, not everyone will see rain during the day, with the driest and brightest weather expected in the South East, which will remain very warm.
The UK Health Security Agency (UKHSA) has issued its first yellow heat-health alert of the year, active until 8am on Sunday in the east of England, East Midlands, London, and the South East.
Under the UKHSA and the Met Office’s weather-health alerting system, a yellow alert means there could be an increased use of healthcare services by vulnerable people.
A yellow alert warns of a possible spike in vulnerable people accessing healthcare, and health risks for the over-65s and those with conditions such as respiratory and cardiovascular diseases.
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While scientists have not assessed the role of global warming in this short-term event, in general they expect more heavy downpours as the climate changes.
That’s largely because hotter air can hold more moisture and so releases more water when it rains.
