Thunderstorms could cause disruption in parts of Wales later, according to forecasters.
It comes as Sunday is set to be the seventh day in a row that temperatures exceed 30C (86F), as the unprecedented September heatwave goes on.
The Met Office issued a weather warning from 14:00 BST to 23:59.
"Unlucky locations" could see up to 70mm (2.8in) of rain in a few hours, along with "frequent lightning and large hail", it said.
"But many parts will see modest rainfall amounts," it said.
Sunday's alert covers Anglesey, Conwy, Denbighshire, Flintshire, Gwynedd and Wrexham.
A separate weather warning covering Ceredigion and Powys has since lifted.
The current heatwave is the longest run of 30C September days in the UK on record.