Met Eireann has issued an updated heavy rainfall weather warning this morning.
The Status Yellow warning applies to Munster, Galway, Mayo and Sligo from today at 3pm until the same time tomorrow.
Particularly heavy rain is expected this evening, overnight and into early tomorrow with falls of 30 to 50mm.
Forecasters say spot flooding is likely and the rain is set to move across the country overnight.
"A wet start on Saturday across much of Ulster and Leinster, with further outbreaks of rain," said Met Eireann.
"The rain will tend to become confined to eastern areas later in the day, but rather persistent here with local spot flooding and fresh onshore winds."
Elsewhere in the country it will be mostly dry tomorrow with some sunny spells, but fog and mist patches will stick around.