Severe winds have today caused widespread traffic disruption, structural damage and the closure of Dublin Port for the first time in 34 years.
Met Éireann has reported strong to gale force southwest to west winds gusting between 100 and 140 km/h in exposed areas. A number of flights and ferry sailings have been cancelled.
The highest winds reported were in Dublin where gusts were recorded at up to 150 km/h.
In Finglas, north Dublin, a man was seriously injured when he was struck by falling debris on a building site early this morning.
The man was working on the building site on the North Road when the accident occurred at 9.30 am. He was taken to the Mater Hospital where he is being treated in the Intensive Care Unit.
AA Roadwatch today warned motorists to drive carefully and be wary of a large numbers of trees and a lot of debris on roads nationwide.
Several traffic diversions are in place in and around Dublin City after two trucks overturned on the North Road in Finglas and on the M1 at the Stockhole Lane Roundabout near the airport.
In the city centre, South Great Georges's Street was closed in the early afternoon after strong winds knocked tiles off the roofs of several buildings. It reopened at around 6 pm this evening.
The Harbour Master at Dublin Port shut down the sea hub for about 30 minutes this morning in the interests of passengers and crew.
Irish Ferries said all Swift sailings were cancelled but that passengers would be accommodated on its cruise ferry service.
It was the first time since Dublin Port Company was established in 1973 that this had happened, spokesperson Brenda Daly said.
"High seas prevented three cargo vessels from berthing and others were unable to get out to sea. Services were delayed as a result." she added.
The Swords Road was blocked between the Coolock Lane interchange and the exit for the Crown Plaza for some time this afternoon, and motorists were forced to take an alternative route.
Trees blocked road across the State. In Meath, the Kilcock to Dunshaughlin Road was blocked by a fallen tree. In Louth felled trees obstructed the N53 Dundalk/Castleblaney Road and on the Dundalk/ Carrickmacross Road.
The Dublin Airport Authority said a number of flights to Dublin had been diverted to Belfast due to strong cross-winds.
It also said a number of internal domestic flights had been cancelled and advised passengers to check with their flight operator before travelling.
In Tipperary, racing scheduled to take place today at Thurles has been cancelled.
