A gust of wind of 100mph has been reported at Donegal Airport this evening as a powerful storm batters the west coast.
The ESB says that 5,000 homes, mostly along the west coast, are without power this evening. It hopes to have electricity restored to most of them later tonight.
A similar number are thought to have lost power north of the border.
It is reported that part of the roof of the Catholic Church at Tulsk, Co Roscommon, has been blown off.
In Donegal, the road between Raphoe and Castlefinn is blocked at Ballymunister by a fallen tree and is impassable.
A tree has also fallen on the main road between Castlefinn and Lifford but the route is passable.
The main Donegal to Sligo road was blocked for a time by a fallen tree which has since been cleared. Gardaí say the route is still dangerous, and that there is a danger of further trees falling.
A number of trees have also blown down near Shercock and Drogheda in Co Louth.
Some buildings in Galway suffered structural damage and some high walls surrounding housing estates were blown down but so far there are no reports of damage to homes.
The main campus of the Galway-Mayo Institute of Technology was closed because of the weather this afternoon.
Driving conditions have also deteriorated in Co Galway and Co Mayo, but it appears that the west has escaped major flooding that had been feared.
The full force of the storm hit the west this afternoon, and is travelling across the country.
In the east of the country, winds appear to have stabilised at 60pmph and no major incidents have been reported.
Met Éireann said all parts of the country would be at risk of damaging gusts, but particularly the northwest.
Emergency services were put on standby on the coast between Galway and Donegal, which was expected to be the worst hit.
AA have warned motorists to take extreme care.
Air and sea services cancelled
The severe weather has led to the cancellation of air and sea services.
Air and ferry services to the Aran Islands have been cancelled, as has tonight's Stena Line sailing from Dublin to Holyhead.
Aer Arann is the worst affected airline, with every flight cancelled for the rest of the night, and at least five further cancellations expected on flights in and out of the west tomorrow morning.
Normal service is not expected before tomorrow afternoon. Passengers are advised to check on 08 18 210 210 before travelling.
Following earlier disruption to Ryanair and Aer Lingus flights, there has been some delays, but no further cancellations.
In Galway, Harbour Master Brian Sheridan appealed to people to stay away from open quays and piers because of the risk of being swept into the sea.
A number of schools in the northwest closed early today.
Last night, six large cargo ships, which had been sheltering in Dingle Bay and the Shannon Estuary, moved away from the coast ahead of the expected storm.
In Malahide in Dublin, a high tide has caused flooding on Bissets Strand, Strand Road and Estuary Road.
RTÉ Agriview recording cancelled
In a separate development, a recording of the RTÉ programme, Agriview, in Athlone in Co Westmeath tonight has been cancelled because of the bad weather.
Ticketholders for the recording due to have taken place at the Hodson Bay Hotel are asked not to attend as it has been postponed to a later date.
