A weather warning remains in place, with high winds, heavy rain and snow forecast for parts of the country.
Stormy conditions have disrupted flights and ferries, while motorists are being warned of fallen debris and surface water on roads.
Flooding and excess surface water are reported on many roads in several counties, including Antrim, Derry, Donegal, Dublin, Kilkenny, Meath, Wexford and Wicklow.
There are major traffic disruptions on the M11 Dublin to Wexford Road, which is closed in both directions between J5 Bray North and J6 Bray/Fassaroe.
AA Roadwatch says the road could be closed until 7pm.
The M50 southbound is closed at Junction 16 in Cherrywood.
It also says road conditions in Dublin are deteriorating this afternoon, with a lot of excess surface water on all routes and flooding especially in the north of the county.
Wicklow County Council has issued a flood alert for the Greystones/Enniskerry Area from today until Monday.
Both quays in Enniscorthy town in Co Wexford are closed as the River Slaney has burst its banks.
Northern Ireland has been worst affected by snowfall, while overnight rain resulted in major flooding in parts of Co Cork.
The runway at George Best Belfast City Airport has reopened after being closed earlier.
All Irish Ferries Jonathan Swift fast craft sailings have been cancelled and passengers will be accommodated on other sailings.
The Stena Line HSS Explorer sailing from Dún Laoghaire to Holyhead at 1.30pm was cancelled.
P&O Ferries is experiencing delays to all sailings between Larne and Cairnryan.
DART services have been suspended south of Dún Laoghaire due to flooding. Dublin Bus is honouring rail tickets.
Bridge Street in Waterford city has reopened following storm damage to a hotel there this morning.
A snow and ice weather warning is in place for counties Cavan, Donegal and Monaghan and will remain in force until the early hours of Sunday morning.
Met Éireann has said there will be further heavy rain today, which could lead to localised flooding in parts of the south and east.
Homes without power in Northern Ireland
Twenty crews from ESB Networks have been dispatched to locations across Northern Ireland to help restore power to homes and businesses, following damage caused by severe winds and blizzard conditions last night.
Hundreds of Northern Ireland Electricity engineers and emergency crews have been working since first light to assess the damage and start the repair process where it has been safe to do so.
Up to 100,000 customers were left without power after overnight weather problems.
Damage has been caused by flying debris and high winds, including broken electricity lines and damage to poles and other equipment.
ESB Networks and NIE have a long-standing arrangement to provide assistance to one another in emergency situations.
Heavy rain sweeping across the North will turn increasingly to snow with up to 30cm across hills in counties Down and Antrim.
Over 70 schools have been closed and snow drifts of up to 40cm have been reported.
Northern Ireland's World Cup football qualifying fixture against Russia, which was scheduled for tonight at Windsor Park, has been postponed until 3pm tomorrow.
UK nuclear power plant Sellafield is being shut down due to adverse weather "as a precaution".
Blackpool hit by overnight floods
Severe flooding was reported in parts of Cork city overnight with Blackpool village badly affected after up to 1.2m (4') of water damaged shops and homes.
It is the second time in less than nine months that Blackpool has been hit by flash floods.
Heavy rain saw large amounts of debris being washed downriver, which blocked a culvert in the middle of the village.
At least 15 shops and homes - many without flood insurance - were damaged.
Two people had to be rescued by Cork City Fire Service from a local off-licence.
Water levels quickly fell as the culvert was cleared and surface water was pumped into a nearby river.
Residents blamed the city council for a lack of maintenance work on the culvert and for not issuing a flood warning.
However, City Manager Tim Lucey said the culvert had been checked twice earlier in the evening and was clear.
He said the flooding was similar to the flash floods in the city last June.
A meeting is due to take place on Wednesday and chairman of the Blackpool Residents Association Bill Dullane, says they will be demanding urgent action on the culvert.
But the City Manager said council staff had checked the site twice last night and found it clear.
He said he will be liaising with the Office of Public Works, who are in the process of drawing up a flood plan for the Lee Valley, about what happened.
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