A man in his 80s has died after flash flooding.
The pensioner's car was submerged in flood water in Walsall in the early hours of Monday, following heavy rainfall.
The Midlands was hit by extremely wet weather on Sunday, with more than a month's rainfall deluging parts of Birmingham in just one hour.
Meanwhile Britons could see the hottest day of the year this Bank Holiday Monday.
More thunderstorms are forecast for parts of Wales and England but the rainfall is unlikely to be as intense as Sunday's, the Met Office said.
A number of people had to be rescued from their homes amid the flash flooding, paramedic Peter Bowles of West Midlands Ambulance Service said, while Warwickshire Fire and Rescue Service said it had been "extremely busy" with flooding calls on Sunday evening.
The Met Office said a site at Winterbourne, in Edgbaston, recorded 58mm of rainfall in just one hour on Sunday afternoon, and 81mm in a 12-hour period.
Birmingham City Council, which said it could not yet put a figure on how many properties have been affected, has advised that while flood water is subsiding in the area, people should take care and beware of debris.
A clean-up operation is underway with extra street cleaning crews working to clear rubbish from affected areas.
Dozens of flood alerts remained in place on Monday morning for the Midlands and some southern parts of England.
The Environment Agency has warned people not to drive through floodwater, reminding people that just 30cm can move a car.
Emergency services were called to the Walsall incident shortly after 2am to find two vehicles in the flooded Lichfield Road in Rushall.
The elderly man was taken to hospital where he later died, but a second person found in the water was unhurt, West Midlands Ambulance Service said.
Further "localised but significant surface water and river flooding is possible" on Monday, an Environment Agency spokeswoman said.
A yellow weather warning for rainfall has been issued by the Met Office, covering, Wales and much of southern and eastern England.
Forecaster Greg Dewhurst said: "I would say pretty much anywhere across England and Wales could see some thunderstorms but they won't be as intense as they were yesterday.
"They could still give some torrential downpours, some localised flooding is still possible, some local hail as well and lightning but they shouldn't be quite as intense as they were yesterday."
The hot weather, which has sparked the thunderstorms, is set to continue on Monday, with temperatures likely to top 29C, Mr Dewhurst added.
The hottest day of the year so far was April 19 when the mercury rose to 29.1C (84F) in St James' Park, central London.