Gardai have issued flood alerts for a number of areas in the east of the country and are advising motorists to allow extra time for journeys.
The M50 northbound in Dublin is currently blocked and impassable at the Ballymun slip road, while there is also difficulty at the Finglas exit.
In the Swords area, Bridge Street, Well Road, Balheary Road and North Street are all impassable and there are delays at the Estuary roundabout, Forest Road and the N1 junction with Turvey Avenue.
Clonshaugh Road, Cloghran Road and Hole in the Wall Road are also closed.
In Blanchardstown, the N3 between the roundabout and Clonee is closed in both directions, with no viable detours due to flooding on all alternative routes.
Mulhuddart village is also severely flooded, with the Hollystown/Church Road junction completely impassable.
Littlepace estate in Clonee is under five feet of water, while Kilshane Cross on the North Road is barely passable.
Rathoath Road/Dunsink Lane is impassable, as are the Cappagh Road at Dolly Heffernan's, Chapelizod village and Knockmaroon Hill.
Gardai said the Naas Road outbound is passable with caution at the Poitin Still in Rathcoole.
The Newcastle/Celbridge Road is impassable at Hazelhatch, while the area around Baldoyle Aerodrome is also off limits to motorists.
Barnhill Road in Lucan, the Lower Lucan Road and Strawberry beds are also impassable, as are Tubber Lane and Confey Lane in Leixlip.
The River Tolka has burst its banks in the north of Dublin city, with Richmond Road/Millmount Avenue closed as a result. Drumcondra Road is passable with caution, but there is serious flooding in the Gracepark Avenue and Gracepark Heights areas. St Margaret's Road is also closed.