Storm Brendan will bring extreme winds and heavy rain today.
Status orange weather warnings are in force for all counties with a status red warning in operation for marine areas.
Winds may reach stronger levels locally and for limited time periods.
Gale force southerly winds will extend countrywide during the morning, with severe and damaging gusts.
Heavy rain will extend from the Atlantic, thundery at times.
There will be coastal flooding due to a combination of onshore winds, spring tides and storm surge.
Clearer conditions, with squally showers of rain and hail, will follow from the west during the afternoon, with the ongoing risk of thunder.
Winds will veer southwesterly with the clearance and ease somewhat, although it will remain windy with stormy conditions persisting on coasts.
Highest temperatures 7 to 10 degrees.
Tonight night will be cold with temperatures falling as low as 1 or 2 degrees despite a persisting fresh southwest wind.
It will be mainly dry with just isolated showers, mainly retreating to coasts of the west and north but at times carried further eastwards by the winds.
There is a status orange wind warning in place for the entire country.
Connacht, Donegal and Kerry will see southerly winds reach average speeds of 65 to 80 km/h - with gusts generally up to 130 km/h - higher in exposed areas.
This alert is in place until 9.00pm on Monday.
For Leinster, Cavan, Monaghan, Clare, Cork, Limerick, Tipperary and Waterford southerly winds will reach mean speeds of 65 to 80 km/h, with gusts generally up to 130 km/h, higher in exposed areas.
This alert is valid until 3.00pm on Monday.
There is also a significant risk of coastal flooding due to the combination of high spring tides and storm surge in all areas.
A status red gale warning is in place on all Irish coastal waters and on the Irish sea, with violent storm force winds expected at times.
Southerly winds will reach storm force during Monday.