Thousands of homes are without power and road travel has been disrupted as Storm Eleanor sweeps in across the UK.
A Met Office yellow warning for winds of up to 80mph (128kph) is in place for Wales, England, most of Northern Ireland and parts of southern Scotland.
More than 12,000 homes have no electricity in Northern Ireland, while there are 2,700 properties without power in England and 460 in Wales.
There are warnings of possible public transport disruption on Wednesday.
Meanwhile, the Met Office says injuries from flying debris are also possible.
Its yellow warning is in force until 18:00 GMT.
BBC Weather presenter Stav Danaos said there would be blustery showers throughout the morning, some of them heavy with hail and thunder.
As Storm Eleanor – the fifth-named storm of the season – approached from the Atlantic, the Met Office raised its threat level from yellow to amber across northern England, Northern Ireland and south-west Scotland.
The warning in place until 04:00 GMT says there is a "good chance" mobile phone coverage could be affected, as well as danger to life from large waves and beach debris thrown onto on coastal roads and seafront properties.
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Earlier, flooding was reported in Galway in the Republic of Ireland, with 97mph gusts in the Irish Republic and 90mph gusts in Orlock Head, Northern Ireland.
On the UK mainland, the Met Office recorded gusts reaching 79mph in Capel Curig in Wales, and 77mph in West Freugh in Dumfries and Galloway.
Northern Ireland Electricity Networks said trees, branches and other flying debris had brought down power lines and poles, affecting homes in southern counties.
In England, almost 2,000 properties are without power in the Midlands, while 700 in the South West and 460 in Wales are with power.
A number of roads have been closed due to fallen trees, including two lanes of the clockwise section of the M25 near Chorleywood in Hertfordshire.
Highways England shut part of the Dartford Crossing – the Queen Elizabeth II Bridge – at 23:00 GMT for safety reasons because of high winds.
But the Dartford tunnel remained operational in both directions and the bridge is expected to reopen before Wednesday morning's rush hour.
The Severn Crossing between Gloucestershire and Monmouthshire and the Orwell Bridge near Ipswich also closed overnight due to the high winds.
The Environment Agency says the combination of strong winds and high tides could cause some coastal flooding in the UK.
Ferry crossings to and from the Isle of Man have been cancelled as forecasters predict wind speeds in that area could reach 70mph.