The remnants of Hurricane Ophelia slammed into Ireland with wind gusts of up to 130 km/h on Monday, killing at least three people, grounding planes, shutting schools and causing widespread power outages.
Irish Prime Minister Leo Varadkar urged people to stay indoors until the storm passed. Tens of thousands of homes were without power and the military was placed on standby. Some hurricane-force gusts were reported 30 years to the day after a weather event dubbed the "Great Storm of 1987" battered southern England.
"It is a very dangerous storm," Varadkar said. "The last time there was a storm this severe, 11 lives were lost," he added, referring to Hurricane Debbie, which hit Ireland in 1961.
Although Ophelia has been downgraded to a post-tropical cyclone, Ireland's National Emergency Coordination Group on Severe Weather warned that the storm is still "unprecedented, with serious life-threatening conditions."
Ireland's weather service, Met Eireann, described the storm as the most powerful on record to have ever been this far east in the Atlantic.
Forecasters warned of flying debris, such as tiles blown from roofs. Large waves around coastal districts tossed sand and rocks onto coastal roads, seafronts and properties.
Wind warnings were in place for Northern Ireland, parts of Wales and western parts of England. Planes were grounded at several locations in the British Isles.
Some 130 flights were cancelled at Dublin Airport, while flights were also grounded at Manchester Airport. Both Ryanair and Easy Jet cancelled flights at Belfast International Airport, with more cancellations expected. Several flights to British airports were also diverted because of unusual odours on board thought to be associated with the remnants of the storm.
Authorities warned anyone with travel plans to contact their airline.
In parts of the United Kingdom and in France's Brittany region, the sky turned an eerie colour as Ophelia's winds carried a mix of sand from the Sahara and particles from forest fires in Spain and Portugal. On social media, people posted pictures of London landmarks against yellow-orange skies.
A non-profit group that provides lifesaving services around the British Isles warned people to stay away from seas and beaches.
Matt Crofts, lifesaving manager for the Royal National Lifeboat Institution, said coastal waters are "particularly dangerous and unpredictable, with large waves and swells being a major risk."
'More powerful than you think'
As tempting as it is to watch crashing surf, it isn't worth the risk of being struck by large waves that can easily knock weather watchers off their feet, Crofts said.
"The sea is far more powerful than you think and your chances of survival are slim if you are dragged into the swell," he said.
And there is more to come Tuesday. Flights and ferries were cancelled in parts of Scotland, and authorities warned of coastal flooding in the southwest. The government of Ireland said schools and colleges would remain closed, and Northern Ireland's Education Authority said the same.
As the storm moved toward Northern Ireland, workers sealed off the Peace Bridge in Londonderry with tape and sandbags, closing it as a precautionary measure.