Thousands of people around the country are facing rising floodwaters this morning.
The AA is advising people to postpone all journeys in Galway and Cork. Severe flooding has also been reported in Tipperary, Kerry, Monaghan, Longford, Kilkenny, Clare, Waterford and Wexford.
The flooding has had a major effect on scheduled bus and rail services, with a number of services cancelled.
More than 200 Defence Forces personnel have been working through the night to help people to build up flood defences and rescue anyone trapped by rising waters.
Sections of Cork city are under water, especially to the west of the city centre. It has been described as the city's worst flooding in 40 years. Gardaí have closed routes in and out of the city.
Lower floors of the city's Mercy Hospital had to be evacuated after water came through the nearby quay wall, bringing down some electrical wiring.
The flooding in the city has been exacerbated by the forced release of water from Cork's Iniscarra dam.
Adrian Spillett, third officer with Cork City Fire Brigade, said there was severe flooding between Wellington Bridge and Grand Parade.