Thunderstorm warnings have been issued for Wednesday as the UK battles the hottest temperatures ever recorded.
On Tuesday, the Met Office issued a yellow weather warning covering swathes of southern and eastern England from 1pm on Wednesday, saying heavy showers and storms could bring disruption to those areas.
Forecasters warned driving conditions could become problematic as downpours lead to sudden flooding and some road closures.
Experts also said there is a "slight chance" towns could see power cuts, homes and businesses could see losses of other services.
Tuesday saw UK temperatures soar into the forties for the first time ever after a reading of 40.2C was recorded at Heathrow.
Scientists have warned that the extreme heat is fuelled by climate change, which is making heatwaves more intense, frequent and likely.
People have been warned to stay indoors, drink fluids, and look out for those who are vulnerable or live alone.
The previous record was 38.7C, which was reached at Cambridge Botanic Garden on 25 July 2019.
Temperatures did not fall below 25°C over Monday night in some places, experts said, which exceeded the previous highest daily minimum record of 23.9°C, recorded in Brighton on 3 August 1990.
Santon Downham in Suffolk saw a peak of 38.1C on Monday, making it the third hottest day on record, after 38.7C in Cambridge in 2019 and 38.5C in Faversham, Kent, in August 2003.
Another record was broken in Wales, as a high of 37.1C was recorded in Hawarden, Flintshire, beating the previous record of 35.2°C, recorded in the same place on 2 August, 1990.
Watch: Forecasters predict worst to come for UK and Ireland