Two people have died, as Storm Ali brings winds of up to 100mph to parts of the British Isles.
A woman died after the caravan she was in was blown off a cliff in the Irish Republic, while in Northern Ireland a man was killed by a falling tree.
Another woman has been seriously injured after a tree fell on a car in Crewe, Cheshire.
Thousands of homes are without power, lorries have overturned and a cruise ship has broken free from its moorings.
The weather warning – which means lives could be at risk – is in force until 17:00 BST.
Storm Ali is the UK’s first named storm of the season.
A man in his 20s was killed and another in his 40s was injured, after a tree fell on them at the gates of Slieve Gullion Forest Park, near Newry, County Armagh.
It is thought the men were working on behalf of Northern Ireland Water.
It is understood the woman who was killed in County Galway was a tourist in her 50s who had been staying at a campsite in Claddaghduff.
Cheshire Police said a woman in Crewe was taken to hospital with serious injuries after a tree fell on a car on the A49.
Elsewhere, a 102mph gust was recorded on the Tay Road Bridge between Dundee and Fife at 15:00.
In Dumfries and Galloway a “major incident” has been declared, as a number of people have been hurt by flying debris.
Children in the area have been told not to walk home from school until the weather subsides.
Dumfries and Galloway Virtual Operations Support Team said some children had already been injured by flying debris.
Earlier, a freight train derailed on the Highland Main Line after striking fallen branches.
And strong winds also caused a cruise ship to slip its moorings in the port of Greenock, Inverclyde.
Oceania Cruises said all guests and crew are safe and tugs have been called in to assist.
About 30,000 homes and businesses are without power in Scotland.
Power-cuts and fallen trees are also causing disruption in Cumbria, where residents have been warned of flying debris.
- The M6 is closed northbound between J43 and J44 after a lorry was blown over
- The Tay Road Bridge between Fife and Dundee is shut
- Dublin Airport has reported 42 cancellations and eight diversions due to high winds – passengers are advised to check with their airline before travelling
- Glasgow Airport has had a number of cancellations and there is further disruption expected at Belfast International Airport
- Virgin trains running between Preston and Glasgow may be cancelled or delayed due to speed restrictions
- All trains to and from Glasgow Central station have been suspended
- ScotRail is is advising against all but essential travel, with a number of routes suspended due to trees on the line or overhead wires being damaged
More than 186,000 homes and businesses are without power in the Republic of Ireland.
In Northern Ireland, about 65,000 homes are without power, while two councils have closed some public spaces because of the storm.
Belfast City Council said it had closed all its parks, pitches and playgrounds, while Derry City and Strabane District Council closed all its parks and cemeteries “until further notice”.
Belfast Zoo was also closed due to the weather.
Dozens of roads are known to have been affected, with a number closed by fallen trees.
A yellow warning – less severe than amber – is in force across the whole of Scotland, as well as parts of North Wales and northern England, until 22:00.
Those areas are likely to experience gusts of up to 60 mph but could face similar levels of danger and damage.
BBC Weather presenter Matt Taylor said the storm could have a greater impact because of the time of year.
He said most trees were still in full leaf and were “acting like sails”, making it more likely they could be pulled over and cause travel problems.
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