A status yellow rainfall alert will come into place this evening for eight counties in Leinster and Munster.
Carlow, Kilkenny, Laois, Wexford, Wicklow, Cork, Tipperary and Waterford are affected.
Met Éireann's warning of heavy rain of up to 30mm and a risk of spot flooding from 8pm tonight until 10am tomorrow.
"Rain will extend to all areas tonight, turning heavy and persistent with a risk of spot flooding especially in parts of the south and southeast of the country," Met Éireann said.
Minimum temperatures of 9 to 13C are expected this evening with moderate south to southeast or variable winds.
Rain is also expected Monday morning with risks of spot flooding.