Up to 1,000 people in Mountmellick, Co Laois have been affected by heavy floods after three rivers burst their banks due to heavy rain.
Earlier this evening, two housing estates were evacuated by emergency services and more than 100 homes have been significantly damaged by the floods.
Hundreds of residents from the town are staying in hotels in Portlaoise.RTÉ
reports that there was no access to the town as roads were closed down during the emergency response.
However, they are now beginning to reopen and the clean up operation is due to begin tomorrow.
Local people have described the flooding as the worst in living memory.
Laois County Council's Director of Services Kieran Kehoe said more than 50mm of water fell in two hours this morning in the Slieve Bloom Mountains, with the village of Clonaslee and nearby Mountmellick feeling the effect of that.
Two schools in Mountmellick - St Patrick's Boys National School and St Joseph's Girls National School - were forced to close on health and safety grounds after the heavy rain and flooding caused a sewage overflow.
Warnings were issued to road users about surface water in many areas following heavy overnight rain.
Dublin Fire Brigade said the Eastern Regional Centre, which takes emergency calls for Leinster, Cavan and Monaghan, received 47 calls this morning, compared to 14 for the same period yesterday, with most being weather-related.
Kildare County Council closed the R445 Naas-Newbridge dual carriageway due to flooding. The closure was in force between the Tougher and Pfizer roundabouts.
Elsewhere, there were warnings of wet road conditions on all routes around Clane in Co Kildare and Ballyheigue, Ballyduff and Causeway in Co Kerry.
There was extensive flooding on roads throughout the midlands, especially on the Birr to Roscrea road, the Clonaslee to Birr road and the Roscrea to Nenagh road.
Local roads in Longford, Westmeath and Laois were also heavily flooded in many areas.
The Road Safety Authority reminded motorists to slow down and allow extra stopping distance on the wet roads.
A number of roads in east Clare were flooded following the heavy rain overnight.
The Scarriff to Mountshannon road was impassable and adjoining fields are heavily flooded.
Heavy rainfall coming down from hills also caused significant flooding near Shanagolden, Mount Trenchard and Glin in Co Limerick and some roads are impassable near Gortadroma.
Fire crews cleared some heavy surface water from Foynes earlier this morning and the road was passable.
Iarnród Éireann says there are delays to some Grand Canal Dock to Newbridge services due to flooding on the line.RTÉ