Weather forecasters have warned of weekend flooding across Derbyshire.
Temperatures are expected to hit nearly 30C in the county today as a wave of hot and very humid air from Spain grips the UK.
However, those stifling conditions look set to trigger intense thunderstorms from tonight and during tomorrow – bringing the risk of “significant” flooding.
The public is advised to take “extra care”.
A spokesman for the Met Office said: “Several areas of heavy, thundery showers will develop from Friday night before moving northwards during Saturday.
“Some torrential downpours are possible with frequent lightning, large hail and strong gusts. Significant flooding is possible.
“The public should be prepared for the risk of disruption from any of these elements and take extra care.”
A spokesman for the Environment Agency added: “Surface water flooding can happen very quickly. It is possible that roads may quickly become impassable and people are urged not to drive through flood water.”
A heatwave alert issued by Public Health England for Derbyshire is in force until Sunday.
Steve Ramsdale, deputy chief meteorologist at the Met Office, said: “Hot and very humid from Spain will see some particularly high day and night temperatures as we head into the weekend.
“The humidity will make it feel close, muggy and uncomfortable for many in the heat and people should take steps to keep cool.”
Dr Paul Cosford, of Public Health England, said: “While many of us enjoy hot weather, high temperatures can be dangerous, especially for those who may be particularly vulnerable such as older people, young children and those with serious illnesses.
“During the day, take care in the sun, don’t over-exert yourself in heat, drink lots of cool fluids and keep an eye out for friends and neighbours. Also, do what you can to minimise your risk of sunburn and try to keep sleeping areas cool.”