Heavy rain and thunderstorms forecast for parts of Wales on Friday
People can expect to see spray and sudden flooding which could lead to difficult driving conditions and road closures.
Train and bus services could be delayed or cancelled in places with flooding and lightning strikes.
There is a slight chance of power cuts, and other services to some homes and businesses could be lost, meteorologists said.
Earlier this week Wales recorded its highest ever temperature of 37.1C in Hawarden, North Wales, where the previous record of 35.2C was set in August 1990.
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