A status yellow rainfall warning has been extended across 14 counties.
The alert is in place for Munster, Dublin, Carlow, Kildare, Kilkenny, Laois, Wexford, Wicklow and Offaly.
Met Éireann says there will be heavy rain at times with up to 35 mm possible, and a risk of localized flooding.
The warning is in place until Sunday morning.
The alert was originally issued for Wexford, Cork, Kerry, Waterford and Donegal.
The forecaster says there will be rain in the southwest which will spread northwards over Munster, Leinster and Connacht this evening.
It will turn heavy at times with a risk of some localised flooding.
Later the rain will continue to spread up over Ulster and will continue heavy over parts of Munster and Leinster.
The rain will become lighter and will clear from the western half of the country by Sunday morning.