About 13,000 homes remained without power after 120 km/h gusts ripped down trees, taking overhead power lines with them, in the latest storm to wreak havoc across Ireland.
Crews were despatched at first light to work on restoring networks in the worst-hit areas of Bandon, Fermoy and Cobh, in Co Cork, Maynooth in Co Kildare, Carnew, Co Wicklow and Athlone.
About 20 businesses were flooded in Bandon, with traders left facing a gruelling clean-up operation. Midleton in Co Cork also bore the brunt, with a number of properties water damaged.
People across the country have been warned about extremely dangerous live electricity cables torn down by Storm Frank.
Motorists were also urged to exercise caution as scores or roads were left impassable by flooding or fallen trees. Major routes including the N4, N11 and N25 were closed at sections.
Torrential rain was at its heaviest overnight and a status orange wind warning was lifted by Wednesday afternoon, but the continuing rise of river and lake levels has maintained fears of further flooding in parts yet to come.
The Government's national emergency taskforce, including Cabinet ministers and State agencies, warned the west of Ireland remains on high alert after weeks of flooding.
"We remain in a severe flooding situation on the Shannon catchment and many of the above other catchments," a spokesman for the National Coordination Group said.
"Ongoing flood defence efforts, for example pumping, will have to continue for some time yet.
"It is also expected that there will be surface water/pluvial flooding on the road network throughout the country for the rest of today and tomorrow."
In Northern Ireland, around 300 homes and businesses remained without electricity during the day after repair crews restored power to 20,000 properties
Dozens of roads were also impassable due to flooding.
Meanwhile, a coast guard helicopter crew battled eight metre waves and strong winds for nearly an hour and a half to rescue a fisherman badly injured at sea by the might of the storm.
The 55-year-old Spanish man suffered head and back injuries when severe sea and weather conditions threw him about while aboard the UK-registered trawler Brisan off the coast of Ireland.
After a mayday call, British authorities asked the Irish Coast Guard to rescue the fisherman 120 nautical miles off the Mizen Head.
Coast Guard helicopters were scrambled from Shannon Airport and Waterford to carry out the medical evacuation.
Despite arriving at the scene at around 10am on Wednesday, it took until 11.23am for the rescuers to safely winch the injured man aboard.
The Irish Coast Guard described the eight metre waves and force six winds as "extremely challenging" during the operation.
The man was airlifted to Cork Airport before being taken by ambulance to Cork University Hospital where he is being treated.