Gardaí have issued specific flood warnings for several areas of Dublin today.
They say the Longmile, Pembroke and Northumberland roads are "severely flooded".
The same goes for Blessington Road in Tallaght, Jobstown, Fosters Avenue, the Chapelizod Road outbound at Palmerstown and Walkinstown Road roundabout.
The Strawberry beds are closed from Larachon to Tinkers Hill, the Slieve Bloom Park area in Drimnagh is impassable, and the Longmile Road is completely flooded, at its junction with the N7.
Cars are stuck in floodwaters on the M1 at Lusk, south of junction 5 on the northbound side.
The centre of Cork city is the worst hit as high tide adds to the floodwaters.
In the city, Morrisons Island, Lavitts Quay, Union Quay, Father Matthew Quay are all impassable and AA Roadwatch is warning that water is coming over the Quay Wall in Youghal.
In Wexford, the N25 Wexford to New Ross Rd at Bergerin Hill is flooded.
The AA also said the N25 Cork to Waterford road is flooded west of Kilmeaden at Carroll's Cross.
Gardaí said all road users need to exercise extreme caution, drive with lights on and allow plenty of time for their journeys.