"Heavy and persistent" rain is set to lash the country today with a risk of flooding in parts.
On Sunday, Met Eireann issued a Status Yellow rainfall warning for Co Clare ahead of the deluge.
It came into effect at 5am today and will last for 24 hours.
The weather chiefs said on their website: "Rainfall accumulations combined with high river levels may result in further flooding."
It will start off dry in the east this morning but rain in the west will quickly spread to all areas this morning.
A forecaster said: "The rain will be heavy and persistent in places, with a risk of local flooding, especially in parts of the west, and it will be misty also.
"Fresh to strong southerly winds veering southwesterly. Cold at first, but becoming milder through the afternoon and evening with highs of 10C to 12C."
A weather advisory for much of the south and west will remain until tomorrow with a risk of flooding due to persistent heavy showers.
The areas affected are Connacht, Longford, Offaly, Westmeath, Cavan, Donegal, Clare, Cork, Kerry, Limerick and Tipperary.
And once the wet spell ends it will be replaced by wintry conditions and sub-zero temperatures bringing severe frost and ice.
A Met Eireann forecaster said: "Wet and windy in many areas at first tomorrow, with rain and fresh and gusty south-westerly winds. Brighter conditions, with a few scattered showers, will extend gradually from the north-west, but rain may return to the south-west later.
“Turning cold from midweek with a risk of frost at night and wintry precipitation at times.
“Cold and windy on Wednesday, with sunny spells and scattered showers, some of hail, with a risk of thunder.
“Turning much colder, with some of the showers turning wintry later Wednesday and Wednesday night.”
And Thursday will see some heavy showers with a mix of rain, hail, sleet and hill snow, and a risk of thunder also.
