The Met Office 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.
People have also been told to expect travel disruption.
A Met Office spokesperson said: "There is a small chance of fast flowing or deep floodwater causing danger to life.
"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."
The Met Office said there is a 'slight chance' that power cuts could occur and other services to some homes and businesses 'could be lost'.
"There is a small chance that some communities become cut off by flooded roads," the weather warning added.