Met Eireann's orange warning will last for four-hours in the early-hours of Sunday morning with dangerous levels of rainfall expected.
The forecaster is predicting "intense" rainfall of up to 50mm between 4am and 8am for Carlow, Kildare, Kilkenny, Laois, Longford, Offaly, Westmeath, Cavan, Donegal, Leitrim, Roscommon, Sligo and Waterford.
A status yellow rainfall for the entire country will come into effect at 1am and last until 10am.