Western and southern areas will be worst affected, with Met Éireann declaring Status Orange for Donegal, Clare, Connacht, Limerick, Kerry and Cork.
Wind speeds in these areas this evening and tonight may reach 90km/hr with gusts of up to 130km/hr along with heavy rain, high tides and high seas, which presents a flooding risk in coastal areas that may remain till this Sunday 5 January.
Cavan, Monaghan, Tipperary, Waterford and Leinster counties should expect winds of up to 80km/hr with 110km/hr gusts with similar coastal flooding risks.
Meanwhile, Met Éireann has declared a Status Orange marine warning for south to south-east gales expected to develop later today on all Irish coastal eaters and on the Irish Sea.
These winds will range from gale to storm force in all sea areas tonight, with "violent storm force" winds on the north-west coast.
Coastal and waterside areas throughout the UK are also on alert for this new wave of "exceptional weather", especially in Devon and Cornwall where waves were reaching nine metres in some spots this afternoon.