Thunderstorms could cause disruption in parts of Wales later, according to forecasters.
It comes as temperatures across the UK could reach almost 33C on Saturday in the UK, making it the sixth consecutive day of the mercury exceeding 30C.
The Met Office has issued a weather warning between 14:00 BST and 21:00.
Up to 50mm (2in) of rain is possible in under two hours and “large hail and lightning are likely additional hazards”, it said.
“While most places will stay dry, a few places may see heavy, slow moving showers and thunderstorms during the afternoon and early evening.”
Saturday’s alert covers Ceredigion, Conwy, Denbighshire, Flintshire, Gwynedd, Powys and Wrexham.
The current heatwave is the longest run of 30C September day in the UK on record.