Parts of Dublin and Cork have been hit by localised flooding after heavy overnight rain.
A combination of downpours and high tides saw parts of Cork city centre reportedly under two feet of water, with the Strawberry Beds near the M50 in the capital also one of the worst affected.
"Gardai are urging all road users to exercise extreme caution, drive with lights on and leave for your destination in plenty of time," said the Garda press office.
In Dublin, the Longmile Road, Pembroke Road, Northumberland Road, Blessington Road in Tallaght, Jobstown, Fosters Avenue, the Chapelizod Road outbound at Palmerstown and Walkinstown Road roundabout were hit by severe flooding ahead of the rush hour.
Slieve Bloom Park in Drimnagh was impassable while the Longmile Road at the junction with the N7 was completely flooded for a time.
Commuters from south Dublin were further disrupted with Dart services stopped between Dalkey and Dun Laoghaire after flooding at Sandycove.
Gardai said a number of cars were stuck on flooded stretches of the Lusk South exit at junction five of the M1.
Weather alerts had been issued by met Eireann on Tuesday night with between 30mm and 50mm of rain forecast to fall along the east and south east coast, with three periods of high tide compounding problems.
Precautions included flood gates on the River Dodder being closed, defences on the Tolka put in place and the Liffey boardwalk closed.
"Coastal areas of the south and east have the added threat of coastal flooding due to a combination of spring tides, high seas, occasional onshore gales and low pressure values," said forecasters.