The Met Office has updated its warning for sever thunderstorms for the South Yorkshire area this afternoon.
The organisation's chief forecaster said: "A hot and increasingly humid airmass now lies across much of the UK.
"This airmass is conducive to isolated thunderstorm development during the afternoon and into the evening.
"With large amounts of energy available in the atmosphere, storms could be severe, with torrential downpours, gusts to 50 mph and large hail of around 1cm in diameter. 20-30 mm of rain is possible in an hour, with as much as 40 to 50 mm possible in 3 hours very locally.
"Large uncertainty remains regarding areas most at risk from storms, and many areas will miss these altogether and stay dry. However, where they do develop, disruption is possible."