The Met Office has this afternoon issued a weather warning for large parts of the country, including Sheffield.
Intense downpours of rain on Friday could see nearly two inches of rain fall in a very short period of time in the worst affected areas.
The warning states: "Rain spreading from the west may turn locally very heavy and thundery from early Friday, with the risk of some torrential downpours very locally.
"Please be aware of the risk of some localised flooding."
The Met Office's chief forecaster added: "A front coming from the Atlantic will merge with warm, unstable air over the country to bring the risk of 30-40 mm in the hour in places and more than 50 mm in a few hours.
"Whilst the vast majority will have much less than this, it could cause disruption, especially if heavier bursts coincide with urban areas."