Flash flooding hit Wales on Monday during thunder and lightning storms that struck throughout the day.
And a yellow Met Office warning for thunderstorms is in force today with the North of England expected to bear the brunt of the unsettled weather which could bring heavy rain after the heatwave.
The Met Office has issued a weather warning covering most of the UK continuing until Thursday evening, although southern parts of the country are expected to enjoy finer weather after heavy rain yesterday.
Forecasters say there is "significant uncertainty in location and timing" of the thunderstorms.
Temperatures should remain warm in Greater Manchester in the mid-20s and it is possible the region may avoid the worst of the storms, which will see scattered storms across the country.
The yellow weather warning across the whole of the UK explains there's a "small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes and large hail."
And it warns of the potential of delays and some cancellations to public transport where flooding or lightning strikes occur.
Spray and sudden flooding could lead to difficult driving conditions for motorists and an increased chance of accidents.
Power cuts could occur - the Met Office explains there's a 'slight chance' this could happen.
And other services to some homes and businesses could be lost during the storms.
It says there's a small chance of fast flowing or deep floodwater causing danger to life in the storms.
And the Environment Agency has issued four warnings for expected flooding in the North West - two at Lancaster and two at Ulverston.
Five flood alerts – warning of possible flooding – are in place for Birmingham and surrounding districts.
Flood alerts have been issued for 19 locations in Scotland, with one also current for the Vyrnwy catchment area in Wales.
London is expected to record a top temperature of 33 degrees this afternoon.
Wednesday is expected to be very hot again in the south.
The Environment Agency said it would update its flood warnings and alerts as the situation changes.
