Near record hurricane winds have been recorded off the north coast as power and communication repair crews battled to reconnect up to 20,000 cut-off homes.
An Atlantic storm brought gales gusting to 91 knots, 165kph at Malin early on Tuesday morning - a speed only surpassed seven times in Ireland, Met Eireann said.
Repair crews spent most of the day trying to return power to 15,000 homes. The worst-affected regions were the north and north-west with about 9,000 blackouts in Donegal and Sligo. The ESB said another 2,500 power losses were reported in Midland counties and another 1,000 in the south.
About 5,000 faults and cut-offs were reported to Eircom, with crews from both companies battling fierce winds into the night to ensure reconnections.
ESB spokesman Brian Montayne said homes hit by cuts should expect to be back on the grid tonight with only the most isolated left without power. "We'd crews out from 4am. The real epicentre of the impact has been the north-west, Donegal, Sligo, Mayo. Crews were working in extremely difficult conditions," he said.
Met Eireann said northern counties were hit by gale force winds on average of between 100kph and 140kph.
Winds were strongest in Connacht and Ulster, with violent storm force 11 battering coasts between Bloody Foreland in Donegal and Fair Head in Co Antrim.
In a posting on its website, Met Eireann said at 5.40am its station on Malin Head, north Donegal, recorded a 10-minute average windspeed of 68 knots, 126kph. That is equivalent to Beaufort scale 12, hurricane force. The previous record for Malin was 67 knots, recorded on December 26, 1998 while the national record of 71 knots, 131kph was recorded at Foynes, Co Limerick, on January 18, 1945.
The 91 knot gust at Malin, recorded around the time the 10-minute average was measured, was just short of the station's record gales of 98 knots, 181kph, from September 16 1961. Met Eireann stressed that the near record figures were based on provisional data.
Storm conditions are expected to moderate as the night goes on.