More than a quarter of a million homes and businesses in Ireland have been hit by power cuts as hurricane force winds swept in from the Atlantic
Roofs were blown off buildings and dozens of trees flattened cars up and down the country while a major emergency was declared in the heritage city of Kilkenny after more than two dozen weather-related incidents.
The Kinsale gas platform off the coast of Cork recorded wind gusting to 96 knots or 178km/h while inland hurricane force winds of 177km/h were recorded.
Shannon and Cork airports closed runways for some time, rail services in the south were disrupted because of debris on lines and trains out of one of Dublin's main stations, Heuston, were cancelled because of a signalling breakdown.
Ireland's meteorology service Met Eireann issued repeated red warnings over the risk from the storm - its highest threat level - as it moved north-east across Ireland.
Cork and Kerry bore the brunt of the storm but the Midlands and Dublin were next in line as the deep but fast moving hurricane force Atlantic depression moved in.
Initially 100,000 homes and businesses mainly along the south and south-west coasts suffered black outs, but as the rush hour commute was in full swing electricity bosses warned the number had more than doubled.
About 200,000 homes and businesses are expected to spend the night without power.
"The gusts that we have measured, they are not record breaking, but they are widespread and there are large areas of the country involved," a spokesman for Met Eireann said.
The storm is believed to be the worst to hit Ireland since the winter of 1998.
Electricity supply chiefs in ESB said they had 2,100 separate faults reported across its network from falling trees, debris and telegraph poles while more than 10,000 communications faults were reported to Eircom, the main landline phone service.
Jerry O'Sullivan, ESB Networks managing director, said the storm was of a different magnitude than anything to hit the country over the last month.
"We are dealing with a situation that is as bad if not worse than anything that we have seen in the past decade," he said.
"ESB Networks crews have been working throughout the day to restore power, however extremely dangerous conditions are hampering their efforts and will mean that up to 200,000 customers may be without power overnight.
Residents in Kilkenny were advised to stay indoors, and also in Limerick where the roof was filmed being blown off the rowing club.
Also in the west a turbo-prop plane was blown off its undercarriage on the taxi stand at Shannon but after several hours of a shutdown the airport reopened as winds abated.
A tornado was reported in Roscommon, with homes and cars damaged by high winds and flying debris from trees and broken fencing.
In Co Kerry roofs were reportedly blown off buildings including a prefab unit in a school.
In Northern Ireland power chiefs warned of possible damage.
A Northern Ireland Electricity spokeswoman said that following the severe weather forecast, with wind gusts of up to 80mph this evening, there was a possibility of damage to the electricity network, especially in exposed southern and eastern locations.
"NIE has initiated an escalation plan and has emergency crews, engineers and call handlers on stand-by," she added.