Up to 40mm of rain is likely today (Friday) and Met Eireann has issued a status yellow weather alert affecting Munster, Leinster and some northern counties.
Rain is to become persistent and occasionally heavy in Munster and Leinster but only showery outbreaks of rain will affect Connacht and Ulster, Met Eireann says.
The rain will die out in most areas on Friday evening and the weather alert is in place until midnight tonight Friday, it says.
Patchy rain and drizzle will return to some southern counties for a time tonight, otherwise remaining dry overnight with variable cloud, Met Eireann says.
Winds will be light to moderate, variable or westerly. Lowest temperatures 2 to 5 degrees Celsius, giving slight grass frost inland further north, it says.
Winds becoming light to moderate, west to southwest and feeling milder and there will be highest temperatures 11 to 14 degrees Celsius, Met Eireann says.
It says Saturday night will be mainly dry and clear, however cloud will increase later with outbreaks of rain and drizzle in the southwest and west.
Rain will become persistent Sunday morning in western counties and this will start to spread further east, Met Eireann says. Rain will reach the east of the country on Sunday evening but will die out in the west, it says.
Sunday will be a mild day but with fresh and gusty, southerly winds, it says.
Outlook for next week
By Monday morning, rain will have died out in all parts of the country and the day itself will continue dry with cloud breaking, Met Eireann says.
South to southeast winds will moderate also and it will become very mild or even warm with the help of sunshine, it says.
It says southerly winds will freshen as the day goes on and will veer westerly, fresh to strong, however, winds will moderate on Tuesday night and showers will mostly die out later.
Met Eireann is likely to start dry and bright but southerly winds will freshen again and a band of rain will sweep eastwards to affect all places during the evening.
Looking to Thursday, Met Eireann says we will see rain clearing to blustery showers but drier conditions may develop going in to next weekend.