Transport links and power supplies across the country are facing major disruption, because of the hurricane-force winds today.
ESB Network crews are working through the night to restore supply to as many customers as possible.
The company says there is a mammoth task ahead as almost 215,000 homes and businesses remain without power.
Tralee, Waterford, Clonmel, Bandon, and Enniscorthy are worst affected.
ESB Network says that priority is being given to making damaged equipment safe and it is warning customers to make preparations for being without supply for a number of days.
Meanwhile, Irish Rail says limited services are now operating again to Cork and Limerick.
Bus transfers are operating to Kerry.
DART services are suspended between Dalkey and Bray due to damage to overhead power lines caused by a fallen tree at Shankill.
Met Eireann forecaster John Eagleton says at the height of the storm, winds were gusting to around 155 kilometres an hour.
Meanwhile in Killarney, 52 occupants of a nursing home were evacuated after its roof was damaged.
Residents of the Waterway Apartments, Ashtown, Dublin, are being evacuated due to structural damage to the property caused by storm damage.
The Ashtown road is closed to traffic and road users are requested to use River road as an alternative.
Gardaí, Emergency Services and Local Authority are at scene.
The Minister for Transport, Leo Varadkar, has chaired this evening's meeting of the National Coordination Group.
He says the worst of the storm is now over and tomorrow should be a much calmer day, which will allow for repairs and clean-ups.
The major emergency which was declared by the Kilkenny County Manager has been stood down.
Gardaí said the major Emergency Co-Ordination Group will remain in place to monitor developments until 10pm.
In Limerick, emergency services are continuing to coordinate the emergency response to hundreds of incidents arising from the severe weather.
Paul Crowe, Director of Services, Limerick City and County Council: “We are advising the public to avoid making any unnecessary journeys as the strong winds are expected to continue into the night-time hours. Motorists are also advised that most roads throughout the City and County are affected by fallen trees and other debris.”
“Individually each agency is following their own emergency procedures. All agencies are stretched but operating within capacity. The Munster Regional Communications centre which is the fire service call centre for the Munster region is being supported by the West and East Regional communications centres,” added Mr. Crowe.
Members of the public wishing to report storm damage of an emergency nature are advised to ring the emergency services on 999.
Around 200,000 households will remain without power overnight in the south and west, because of damage to power lines in bad weather.
At the height of the storm, 260,000 homes were out, and crews are now working to restore supply.
Update: Limited services resuming between Cork/Kerry/Limerick and Heuston subject to delays— Iarnród Éireann #StaySafe (@IrishRail) February 12, 2014
CORK CITY: The South City Link Rd has reopened and delays are expected to ease. #AARW— AA Roadwatch (@aaroadwatch) February 12, 2014
Gardaí in Dublin have detailed some of the roads that are closed due to the bad weather:
ESB cable down on Rathgar Avenue
Tree down blocking rd on Lwr Dodder Rd Orwell Rd end Rathgar
Ballinclea Rd Tree fallen onto Rd
Tree down at Kevin St/ Patrick St.
Several Trees have fallen down on Shelerin Rd Clonsill D15
Trees down on the Moyne Rd Baldonnel between Fingal Cemetery and Champions Public House.
Tree down on the Coast Rd also wire down.
Annavill Rd Closed due to falling slates
Tree down at Jct of Rathbeale Rd and Ballyboughal Rd
Clonshaugh Rd closed for the night.
Clare County Council say emergency services are responding to more than 150 separate weather related incidents around the county.
An emergency number - 1890 252 943 - has been established for members of the public to report fallen trees, blocked roads and flooding. This number will be operational until 7.30pm.
The southeast of the county is one of the worst affected areas, particularly in Killaloe and around Sixmilebridge, with fallen trees reported on most routes throughout the region.
The north and west of the county have also been badly affected.
Clare County Council says it expects storm conditions to abate later this evening but it is urging members of the public to avoid making any unnecessary journeys due to storm debris and traffic lights out of operation on the county’s roads.
Eircom says at least 11,500 customers are currently without service in the south, south west and west of the country.
The company says it expects the number of faults to rise significantly and eircom says services are unlikely to be restored this evening.
No trains btwn Dub & Cork, Kerry, Limerick; btwn Limk & Athenry. Delays all lines as trees/debris cleared. Full info: http://t.co/o3ETFl3mdM— Iarnród Éireann #StaySafe (@IrishRail) February 12, 2014
An Post says some mail collection and delivery services have been affected.
Power outages are causing service disruption at a large number of Post Offices across counties Kerry, Limerick and Clare.
The company says as the storm moves across the country, Retail and Mails services in other areas may be affected.
An Post says it is continuing to monitor the situation in all parts of the country this evening and overnight with a view to resuming services as soon as it is safe, and logistically possible, to do so.
DUBLIN A number of fallen trees around Blanchardstown.Gardai say care also needed around Tyrellstown & Clonsilla http://t.co/r19oH1cxgs— AA Roadwatch (@aaroadwatch) February 12, 2014
People are being urged to stay indoors as "Storm Darwin" causes buildings to collapse, trucks to overturn and widespread chaos to the transport network.
The County Manager for Kilkenny city has declared a Major Emergency Plan for the city and county due to the stormy weather.
TIPP-Gardai advising motorists not to make unnecessary journeys; over 40 roads blocked due to fallen trees& ESB lines http://t.co/nqdTLmlPQj— AA Roadwatch (@aaroadwatch) February 12, 2014
Gardaí are appealing to the public in Kilkenny to stay indoors and to avoid unnecessary travel where possible.
The Emergency Services are currently dealing with more than 24 incidents in Kilkenny city involving fallen trees and fallen power lines.
The following roads are currently impassable: College Road; Castle Roadl; Dublin Road (near McDonagh Junction); Green Street and Freshford Road.
A number of warnings have been issued to people to avoid unnecessary travel, particularly in Counties Cork and Kerry.
The eastern seaboard is expected to bear the brunt of the storm later this afternoon while the storm is expected to track north east across the country this evening.
More than 260,000 homes are still without power that number is expected to rise through the day.
ESB Networks say crews are battling against dangerous conditions which are hampering repairs.
The National Co-ordination Group expects the worst of the conditions in the east to have passed by around 7pm.
Met Eireann has upgraded its weather warning for Leinster to a status red alert.
Gardaí say many trees are down in Kilkenny and traffic diversions are in place around the city.
The ring road is completely closed on the Dublin side.
Students at a Co. Wexford school have been told not to leave the building after the roof of a nearby swimming pool blew off.
A 'substantial' portion of the recently refurbished pool in New Ross has blown down onto the surrounding area.
No one was hurt by the school is keeping students and staff inside as a precaution because of the amount of debris.
Two units of the Fire Brigade are at the scene.
Cork: Approx 16km tailback on N20 into Mallow from Buttevant. Truck jack-knifed. Going to be there for few hrs. http://t.co/qvBPcgxUj8— AA Roadwatch (@aaroadwatch) February 12, 2014
The main Cork to Dublin road, the M8, is closed both ways after a truck overturned on the Fermoy flyover.
No Irish Rail services are operating between Mallow and Cork, Mallow and Tralee and between Cork, Cobh and Midleton because of debris on the line.
There are trees down on roads across the southern half of the country, so extra care is advised.
CORK CITY: Lee Rd is now impassable due to flooding; the river has burst its banks.— AA Roadwatch (@aaroadwatch) February 12, 2014
More than 95,000 homes are without power as a result of the violent storm conditions.
ESB networks say they expect this number to rise and are warning that crews are reporting extremely dangerous working conditions which are hampering repairs.
In Limerick, part of the front of a building has collapsed in Sarsfield Street.
Bricks fell onto a car in the street, but the driver escaped uninjured.
This video clip from Limerick city Fire and Rescue shows the roof being blown off a boat storage facility at Limerick Boat Club.
Conditions in the mid-west of the city are described as "like a hurricane".
Waterford Airport has reported winds gusting to 81 knots or 150km/h.
And in the west, Shannon Airport said it had been forced to close due to the adverse weather conditions.
More than 95,000 homes are already without electricity, mostly along the south and west of the country, after the latest Atlantic storm swept in.
Closures have hit Irish Rail services with customers on all routes in Cork and Kerry warned to expect disruption and significant delays.
The operator blamed fallen trees and debris on lines including the routes from Mallow to Cork and Tralee and Cork to Cobh/Midleton.
“Due to fallen trees on roads, it is currently not possible to provide bus transfers between Mallow and Cork, and between Mallow and Tralee,” Irish Rail said.
“Line maintenance crews are working to clear train lines, to ensure customers are brought to their destinations at the earliest opportunity. However significant delays can be expected.”
Among the worst-affected areas are Cork, Kerry and Clare after Met Eireann issued its highest-evel red warning.
ESB said the number without power is expected to worsen as the storm sweeps across the country with gusts of up to 160kph (100mph).
Repair crews said that working conditions were extremely dangerous.
The electricity supplier said it has already restored connections to more than 5,000 customers today.
“However, efforts will be hampered by the severity of the storm as safety is a prime consideration,” an ESB spokeswoman said.
“Where possible, our remote network operational capability will be utilised to isolate faults and restore supply as quickly as possible.”
In Cork, Skibbereen, Bandon, Bantry, Banteer, Castletownbere, Clonakilty, Kinsale, Macroom, Roscarrbery and Timoleague are badly hit.
Killorglin, Milltown and Beaufort have been severely disrupted in Kerry, while Ennistymon in Co Clare is without supply.
A tornado was reported in Roscommon, with homes and cars damaged by high winds and flying debris from trees and broken fencing.
Winds gusting to 111kph (69mph) were recorded by the Marine Institute’s databuoy M5 off the south east coast by midday.
Eircom said it has about 11,000 faults on its telecoms lines but they are not all related to the storm.
The company said it expects its figures to change as more people report issues on individual lines over the next 24 hours, mostly in southern regions.
ESB said it is continually assessing the scale of the damage.
“However, even at this stage we can expect that if the weather is too dangerous for crews to work until late in the afternoon, there is a risk that some homes and businesses may unfortunately be without power overnight,” the spokeswoman said.
No services currently operating between Mallow/Cork, Mallow/Tralee and Cork/Cobh/Midleton due to debris on the line.— Iarnród Éireann #StaySafe (@IrishRail) February 12, 2014
Met Eireann forecast storm-force southerly winds of 60-70kph (37-43mph), gusting to 120kph (75mph), before worsening during the day with the peak of the storm to pass mid-afternoon.
Meanwhile, road safety chiefs urged people to use caution when travelling.
They said road users should be mindful of excess surface water and risk of floods in places and urged them to check local weather and traffic reports in the area before making a journey.
Trees and telegraph poles were reported down in parts of Cork, Kerry, Tipperary and Clare, while AA Roadwatch said it had reports of flying debris on the Dingle peninsula, including shed roofs.
Elsewhere, a truck overturned on the M8 northbound between Fermoy and Mitchelstown.
A number of flights were diverted from Cork airport or cancelled.
Met Eireann had a level orange alert in place for Wexford, Galway, Mayo, Clare, Limerick and Waterford, warning of severe winds and high seas while a level yellow alert is in place for the rest of the country.
ESB said it was the worst mass power outage to hit Ireland for more than 15 years.
“It was 1998 the last time the outage scale was as high as this,” an ESB spokeswoman said.