A severe weather warning for heavy rain has been issued for South Yorkshire.
The yellow warning - which applies to the early hours of Bank Holiday Monday, between midnight and 6am - is for heavy rain with the possibility of flooding.
The Met Office say flooding of homes and businesses could happen quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
Fast flowing or deep floodwater is also possible, causing a danger to life
Spray and sudden flooding could lead to difficult driving conditions and some road closures and some communities might become cut off if roads flood
Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
Power cuts might occur and other services to some homes and businesses could be lost
A Met Office spokesperson said: "Thunderstorms will continue to develop over the southern half of the UK throughout Sunday with some of these persisting into Monday morning.
"Whilst many areas will see small amounts of rain a few locations may see some very large totals with 30 mm possible within an hour and perhaps up to 80 mm in 3 hours.
"Along with this hail and thunder are likely as well as some locally strong gusts.
"Perhaps the most likely time and location for seeing these severe thunderstorms is over parts of Wales and extending southeastwards into southern parts of the Midlands during Sunday afternoon."