A yellow thunderstorm warning has been issued by the Met Office for Friday, including areas of South Lincolnshire.
Most areas will be dry on Friday, July 20 between 2pm and 11.5pm, but there is potential for slow-moving thundery downpours in some places, the Met Office said.
Forecasters said: “There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater.
“Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train, bus and tube services, particularly during the evening rush hour.
“Spray and sudden flooding could lead to difficult driving conditions with the possibility of road closures.
“There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.”