The strongest gusts ever recorded in Northern Ireland in June have caused travel disruption and left tens of thousands of households without power.
Storm Hector saw unusually strong winds of 50-70mph batter the whole of the island overnight.
North of the border, more than 23,000 suffered disrupted electricity supply while over 300 incidents of weather-related damage to the network were recorded including broken lines and poles.
Orlock Head in Co Down was buffeted by 74mph winds at 7am on Thursday, the Met Office said.
A yellow warning will remain in place until 3pm, but the worst has passed.
A spokeswoman added: "By Thursday evening the low pressure system which brought the strong winds will be moving out towards the North Sea."
Northern Ireland Electricity (NIE) said that by noon on Thursday, more than 19,000 customers had had their power restored, with 4,000 remaining without.
Edel Creery, head of communications at NIE Networks which maintains the power infrastructure, said although there has been damage to the network, the repair process is progressing well.
"The damage caused by Storm Hector includes power lines brought down by falling trees and poles broken by the high winds," she said.
"We have been working in difficult conditions throughout the night to restore power to customers and we'll continue to respond to reports of damage and reconnect supplies as quickly and safely as possible.
"Our main incident centre in Craigavon and Local Incident Centres in Northern Ireland are open and will co-ordinate the local repair process until all customers are back on supply.
"If you are without power and you have not yet reported the disruption to NIE Networks, please report the fault online at nienetworks.co.uk or call our Customer Helpline on 03457 643 643."
Roads in Bangor, Dungannon, Gilford and Lurgan were closed by fallen trees or debris.
Belfast Harbour said two cruise ships, the Nautica and the Eclipse, were unable to berth due to the conditions.
In the Republic, almost 35,000 homes, farms and businesses were left without power.
Damage was caused by fallen trees on overhead lines, Ireland's electric board ESB said.
Counties worst affected included Galway, Mayo, Sligo and Donegal, as well as Cavan and Monaghan.
ESB said its teams were working to restore power to all impacted families throughout Thursday.
It warned the public not to touch fallen wires or damaged electricity network and to report any incidents.