Around 100,000 homes and businesses are without power as Storm Debi sweeps across the island of Ireland.
Heavy winds and fallen trees have been reported across the country as local authorities begin to assess the damage.
There has been coastal flooding in Galway City and nearby Oranmore.
The ESB said it would have to work late through the night to return power to customers.
Forecasters had warned of a potential “danger to life” as schools in parts of Ireland delayed opening due to weather warnings across the island.
A yellow warning for every county in Ireland came into effect at midnight and is due to remain until 3pm on Monday.
The majority of the country was also placed under a series of now-expired red and orange wind warnings due to “severe and damaging gusts”.
Dublin Airport warned the weather “may cause some disruption to early morning flights”, while the Luas said there will be no Red or Green Line tram services operating before approximately 10am.
Dublin Coach said a number of its services had been cancelled because of the weather warnings with updates to be provided throughout the day.
Dublin Bus said none of its services will operate before 10am on Monday due to Storm Debi, and there will be a phased return with some disruptions later in the day.
An ESB spokesman said approximately 100,000 customers were without power supply at 7.45am on Monday due to Storm Debi.
Brian Tapley, of ESB Networks, said the worst affected areas are Tuam, Longford, the Midlands, Ashbourne and Navan.
“Obviously, the storm is still impacting different parts of the country so we’ll be slow to send out crews until it is safe to do so, but any emergency calls are being attended to,” he told RTE Radio.
A gust of 115kph was recorded at a Met Eireann weather station in Athenry, Co Galway, on Monday morning.
Junior minister Patrick O’Donovan said the scale of the damage will be clearer later in the day.
Mr O’Donovan, who has responsibility for the Office of Public Works, said the advice is to drive with extreme caution for those who leave their homes in areas where a weather warning was or is in place.
“The local authority crews will only start going out in the last while when the Red warning was lifted in some counties and when first light is achieved they’ll be able to see the scale of the damage.
“We won’t be able to ascertain the full damage until later on in the morning.”
He asked people to leave it to local authority workers and ESB workers to clear trees from the roads.
“The warning really to people that are going to go out on the roads is to stay away from trees because they could be very easily entangled with power lines and there is other risks associated with trees,” he told RTE Radio.
This is the fourth storm to affect Ireland since September, which saw main streets in Ireland hit by flooding after intense rain from Storms Babet and Ciaran.
The Irish national director for fire and emergency management said Storm Debi is “probably the most intense storm” of the season so far.
Keith Leonard said: “It was probably the high winds of that leading edge of the storm as it came across the country that was the most hazardous piece. So probably the most intense storm we’ve had so far in the season.”
He said there is a “general trend” of coastal flooding.
He told RTE radio: “But thankfully not too much structural damage being reported at the moment.”
The National Emergency Co-ordination Group is due to meet at 11am.
The UK Met Office has also issued a yellow wind and rain warning for all of Northern Ireland on Monday, while an amber warning will apply to counties Down and Amragh.
The yellow warning came into effect at 3am on Monday and applies until 2pm, while the amber warning is in effect from 6am until midday.
The Met Office said heavy rain and strong winds may bring disruption and flooding to parts of the region.
It advised people to be aware that homes and businesses could be flooded and there could be disruption to bus, rail and air travel.
The agency also warned that fast-flowing or deep floodwater and flying debris could cause a danger to life.
Meanwhile, in Northern Ireland there has been disruption to travel and approximately 3,000 homes are without electricity.
A number of roads have been closed in the Ballymena area and Translink said the bus station in Lisburn is closed.
The storm arrived just days after Newry, Downpatrick and Portadown suffered significant flooding.
