A Status Yellow rainfall warning has been issued for the entire country with persistent and heavy bands of rain expected.
Heavy rainfall will begin from Sunday night through to Tuesday evening, according to Met Éireann.
The national forecaster said that while some areas will remain below warning levels, there is a risk of localised spot flooding with a heightened risk of flash flooding in mountainous regions where accumulations are expected to be highest.
The warning is valid from midnight tonight until 7pm on Tuesday.
This afternoon, it is expected that there will be sunny spells in many areas across Munster with patchy rain expected across the southwest.
Outbreaks of rain across the province are expected this evening with highest temperatures of 12 to 15 degrees.
Tonight will be cloudy, with patchy light rain or drizzle developing into persistent rain which will move into southwest Munster overnight and will spread northeastwards. Lowest temperatures of 10 to 12 degrees are forecast.
Monday is set to be cloudy, wet and breezy at times with persistent and heavy rain affecting most parts of Munster throughout the morning and early afternoon.
There will be drier intervals in the afternoon, but further persistent rain will move in from the southwest by evening with highest temperatures of 12 to 14 degrees.
Monday night will see widespread persistent rain maintaining the risk of river and surface flooding, turning drier with some clear spells developing throughout the night.
Tuesday will bring with it low pressure causing strong southerly winds with outbreaks of heavy rain forecast.
Drier conditions will then develop on Tuesday night with temperatures decreasing to between 7 and 10 degrees.