Heavy rain and thunderstorms could bring disruption across parts of Wales on Christmas Eve.
Forecasters have warned buildings could be damaged by lightning and there may be some power loss.
A warning has been issued across south Wales along with parts of Ceredigion and Powys by the Met Office between 05:00 and 13:00 GMT.
Lightning strikes have been reported in the Llandeilo and Milford Haven areas, and wind gusts have been increasing.
Speeds of 45mph have been recorded in Pembrokeshire, Carmarthenshire and Mumbles.
The Met Office said gusts of up to 60mph, hail and standing water could cause problems on roads and public transport.