The forecaster has warned of thundery downpours in places
Met Éireann has issued a status yellow rainfall warning for 16 counties.
The alert is in place for Leinster, Cavan, Monaghan, Donegal and Waterford.
The forecaster says thundery downpours in places may lead to rainfall accumulations of between 25 to 40mm.
The warning is in place from 9.00pm Friday until 9.00am Saturday morning.
A seperate weather advisory is in place for Munster and Leinster.
The status yellow advisory says soil moisture deficits will remain in excess of 70mm in many parts of Leinster and Munster.
The change comes as Irish Water confirmed an extension of the hosepipe ban and water pressure reductions in the greater Dublin area.
The Irish Water Board met on Friday to discuss the situation - where both water engineering experts within local authorities and Irish Water agreed that the situation will remain critical up to and possibly beyond mid-August.
A Water Conservation Order, or hosepipe ban, is also in place nationally until August 31st.
While water pressure reductions for Dublin will continue for another two weeks.
The most severe conditions continue to be in the east and south, where the rivers, lakes and groundwater tables are at record lows.
Met Éireann has indicated that the short-term rainfall will not be at a level that will assist the recovery of raw water sources.