A Status Yellow rainfall warning has been issued for Cork and much of the western half of the country.
Met Éireann forecasters say 25 to 35mm of rain is expected tonight and into Saturday morning.
They warned of spot flooding in places and that the rain may turn to snow in some parts.
The warning is in effect for Connacht, Longford, Offaly, Westmeath, Cavan, Monaghan, Clare, Cork, Kerry, Limerick and Tipperary
It is valid from 9pm tonight until 12 noon tomorrow.