Tens of thousands of homes and businesses across the island of Ireland lost power overnight as Storm Eleanor swept in.
In the Irish Republic at least 55,000 properties experienced blackouts as the winter storm battered the network.
In Northern Ireland more than 20,000 customers, mainly across the border counties, were left without power at the height of the gales.
Winds of up to 100mph wreaked significant damage and caused flooding on the Atlantic coast.
Parts of Galway city were submerged in the rising waters. Flooding also hit Salthill, Oranmore and Clarinbridge as high tides combined with gale-force winds.
Some cars were abandoned in Oranmore as roads were blocked while others in a car park in Salthill were partially submerged.
ESB Networks said counties worst affected in the Republic included Galway, Mayo, Sligo, Leitrim, Cavan and Monaghan. Across the island, fallen trees forced road closures.
North of the border, there were 400 separate incidents of damage to the electricity network.
Engineers worked through the night to restore power to thousands of customers. By 7am, 3,000 remained without supply in Northern Ireland.
Julia Carson, from Northern Ireland Electricity (NIE), said: "The damage caused by Storm Eleanor includes power lines brought down by falling trees and poles broken by the high winds.
"We have been working in difficult conditions since yesterday evening to restore power to over 20,000 customers and we'll continue to respond to reports of damage and reconnect supplies as quickly and safely as possible."
In Galway, streets around the docks were flooded after high tides breached defences and inundated the areas around the Spanish Arch, Claddagh, Dominick Street and Quay Street.
Water was more than 1ft deep in places.
The Coast Road from the city to Oranmore was also impassable at rush hour on Tuesday as high tide combined with the strong winds to cause local flooding.
In Gort, Co Galway, households were warned about potential disruption to water supplies after power cuts hit the local pumping station.
There were also reports of spot flooding on the N85 Ennis to Ennistymon road in Co Clare.
In the Irish Republic, a Met Eireann orange wind warning remained in place for Wednesday morning for counties Donegal, Galway, Leitrim, Mayo, Sligo, Clare, Cork, Kerry and Limerick.
The forecaster said: "Westerly gale to storm winds together with high tides and exceptionally high seas will result in coastal damage and flooding. Damaging gusts likely inland also."
A Met Office yellow wind warning affecting all of Northern Ireland was due to lift at 6pm.