Storm Callum is on the way and will bring heavy and persistent rain and strong winds on Friday with gusts of up to 60mph around coasts and hills are also forecast. Further heavy rainfall is expected on Saturday.
The storm which is currently gathering over the Atlantic will hit south Wales especially hard before heading North with warnings that a month’s worth of rain could fall in just two days.
The Met Office said that “Leaves and twigs, brought down by the wind, could block drains and culverts, increasing the likelihood of flooding”.
Natural Resources Wales warned that weather conditions at sea could also cause flooding with large waves, strong winds and a tidal surge.
Arriva Trains are cancelling several train services across Wales including between Llandudno Junction and Blaenau Ffestiniog on both Friday and Saturday.
Energy companies have also warned of the possibility of power cuts in North Wales.
The Met Office warning runs from 5:00am on Friday until midnight on Saturday.