A status yellow weather warning for heavy rain is set to remain in place until Sunday morning in some parts of the country.
Between 50mm and 80mm of rain is expected to fall, according to Met Eireann.
The weather warning, which came into effect on Friday, March 17, is set to remain valid until 9am on Sunday morning, March 19.
Today, Saturday, is set to be mild and cloudy with further rain.
In the afternoon, rain is expected to become light and patchy in many areas. But it is likely to turn heavy at times in Ulster and north Connacht.
Highest temperatures of 11 to 14 degrees are forecast, with moderate to fresh southwesterly winds set to strengthen on Atlantic coasts in the evening.
Overnight it is expected to be windy, cloudy and misty, with rain in many areas.
The rain is likely to be heaviest in Atlantic coastal counties, with some spot flooding, where the fresh to strong southwest winds are forecast to reach gale force.
Some hill and coastal fog is also likely; with temperatures dropping to between 7 and 10 degrees.
According to Met Eireann, drying conditions will be reasonable during the coming days for the east and south, but will be poorer in the west and north.
Field conditions may improve a little in well-drained and moderately drained soils in the east and south. But, poorly drained soils are set to remain saturated.
Sunday
Tomorrow morning, Sunday, is forecast to be cloudy, misty and breezy, with some further rain.
There is a possibility this rain may turn heavy at times, but it is likely to ease off and become more scattered during the second half of the day.
Meanwhile, it is expected to be windy, mostly cloudy and misty early on Sunday night.
Some heavy showers may hit Atlantic coastal counties.
Later in the night, conditions are set to turn fresher, more showery and less windy as temperatures drop to as low as 4 degrees.
Outlook
Indications suggest that the early days of next week will be cold, breezy and showery.
The showers are forecast to turn wintry in places on Monday night and on Tuesday, with some snow in places.
Frost is also expected to return; with some icy roads likely as well, according to Met Eireann.