A yellow "be aware" warning of heavy rain is in force for South and South West Wales.
The Met Office says the ground is already wet so with 10 - 30 mm of rain likely there is a risk of localised flooding.
The areas affected are: Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Carmarthenshire, Merthyr Tydfil, Neath Port Talbot, Newport, Pembrokeshire, Rhonnda Cynon Taff, Swansea, Torfaen, Vale of Glamorgan
The Met Office has issued a yellow "be aware" warning of heavy rain in South Wales.
It says 15mm to 25mm could fall in six hours and up to 40mm on high ground.
The areas affected: Swansea, Bridgend, Neath Port Talbot, Vale of Glamorgan, Rhonnda Cynon Taff, Cardiff, Caerphilly, Merthyr Tydfil.
The Met Office says there is a risk of localised flooding.
There's a "be aware" warning from the Met office of heavy rain for the whole of Wales.
Forecasters say there could be locally torrential downpours in places.
Localised flooding's also a possibility.
There is rain, surface water and reduced visibility on the M4 between J30 A4232 (Cardiff Gate) and J23 M48.
The Met Office has issued a yellow "be aware" warning of rain for parts of Denbighshire, Flintshire, Wrexham, Conwy, Gwynedd and Powys.
It says up to 4cm is possible.