Thunderstorm warnings have been issued by the Met Office across England and Wales for Saturday afternoon and continuing into the evening.
A yellow weather warning is in place between 1pm and 8pm, covering large parts of Wales and south-west England.
It means that sudden flooding could occur in the affected areas, as well as slow-moving heavy showers, causing disruption to transport and roads.
“Spray and sudden flooding could lead to difficult driving conditions and some road closures,” the Met Office said. “There is a small chance that some communities are temporarily cut off by flooded roads.”
It added: “Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services. There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from flood water.”
Some areas could see up to 30mm of rainfall in the space of a couple of hours, although the showers and thunderstorms are expected to gradually fade during Saturday evening.
People living in areas likely to be affected by thunderstorms are advised to check whether their property is at risk and, if so, to devise a flood plan and prepare an emergency flood kit.
Other advice includes to charge mobile-phone devices, park cars outside the flood zone, store valuables high up and turn off water and gas supplies.
The Met Office also advised people to secure loose items, such as bins, plant pots, trampolines and garden furniture, and to lock shed doors. People should also prepare torches and candles in case of a power cut, it said.
It added: “It is not safe to drive or walk or swim through flood water, avoid it where possible and if you are affected by fast-flowing or deep water, call 999 and wait for help.”
