The Met Office has issued yellow weather warnings for Northern Ireland and Scotland.
The weather warning comes into effect from midday on Sunday and lasts until 6am on Monday morning.
The weather agency says that while some places will stay dry, hit-and-miss thunderstorms will develop on Sunday and Sunday night, and may bring disruption in places.
Their warning said: "There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.
"Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
"Spray and sudden flooding could lead to difficult driving conditions and some road closures.
"There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost."
The warning then extends to Wales and most of England from 6am on Monday through to midnight.