Thunderstorms may hit parts of Britain as forecasters warn of heavy rain and the threat of sudden flooding.
The Met Office has issued a warning for rain across parts of England and Wales from early on Thursday morning, and while these isolated thunderstorms may miss many places, other areas face "intense downpours".
Forecasters are warning that the storms will bring the threat of roads, transport routes, homes and businesses being flooded, while lightning and hail may hit some parts.
Temperatures are expected to remain high, with the London area potentially seeing the mercury rise to 31C (87.8F) on Thursday, after 29.5C (85.1F) was recorded at Heathrow on Wednesday.
Greg Dewhurst, a forecaster at the Met Office, said the risk of thunderstorms is likely to develop during the night mainly across the south coast of England, before pushing into the London area at around 6am on Thursday.
By lunchtime, East Anglia and Cambridgeshire are likely to be affected, and further thunderstorms are likely to develop across parts of Yorkshire, the Pennines, the Midlands and eastern parts of Wales.
Unstable air and high temperatures will trigger the thunderstorms but Mr Dewhurst added: "Not everywhere will see them. There will be lots of places that will stay dry."
Chris Wilding, flood duty manager at the Environment Agency, said: "Thunderstorms and intense, heavy rain are possible across parts of the country on Thursday and in eastern England during the early hours of Friday morning.
"This could lead to localised flooding and disruption to travel, particularly in urban areas.
"Environment Agency teams are out on the ground and will support local authorities in responding to surface water flooding.
"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 and cause an accident."