Flooding has resulted in the evacuation of a number of homes and the closure of roads and bridges in Co Wicklow.
Met Éireann says more than 30mm of rain fell in some parts of the south and southeast overnight.
AA Roadwatch is advising motorists to drive with extreme care.
In Bray, a number of houses were evacuated early this morning.
Around nine houses off Old Connaught Avenue were flooded at around 4am. The residents of three of the houses, including two men with disabilities in their 70s and a family with two children, had to leave with the assistance of the local fire brigade.
A large walled garden, used by people attending the Festina Lente day care project for adults with intellectual disabilities, was also badly flooded and management have warned it will have to close temporarily as a result.
This morning, it was estimated there was around 2.1m (7’) of water trapped inside the walls of the garden.
Meanwhile, the river Vartry has burst its banks between Ashford and Rathnew. As a result, Mount Usher Gardens has been badly flooded.
Head Gardener Sean Heffernan said almost the entire width of the gardens is covered in water. The level of water is almost as bad as the flooding that happened during Hurricane Charlie, he said.
Gardaí are advising motorists to avoid Arklow town until further notice. The main bridge has been closed because of the volume of water passing under it.
Engineers from Wicklow County Council, the Civil Defence and gardaí took the decision to close the bridge earlier this morning and are now monitoring the structure.
There have also been reports that a 40ft container has been seen in the water further upriver, which it is feared could damage the bridge if it struck it.
A number of houses and premises in the town were also flooded earlier today.
The Avoca river, which passes through the Co Wicklow town, is heavily swollen with rain water and melted snow from the hills and has burst its banks in places.
The area from Vale Road to Aughrim is completely flooded and will be closed for some time.
Iarnród Éireann says bus transfers are in operation between Wicklow and Arklow on the Dublin to Gorey/Rosslare line due to flooding.
In Clonmel, Co Tipperary, Convent Bridge and the Quays are closed due to flooding.
In Enniscorthy, Co Wexford, the quays have been closed and diversions are in place around the town. People have been asked to avoid the area completely. Gardaí have removed all cars parked on both sides of the quays because of flooding.
AA Roadwatch is also reporting excess surface water in counties Carlow, Kildare, Kilkenny, Monaghan and Waterford.