Storm Eunice made landfall in south-western England on Friday morning and extreme conditions ensued as it swept towards the country's biggest and richest city.
Three people in Britain were killed, including a man in southern England killed when a car hit a tree, another man whose windshield was struck by debris in northwest England and a woman in her 30s who died in London when a tree fell on a car.
Elsewhere, falling trees killed three people in the Netherlands and a man in his 60s in southeast Ireland, while a Canadian man aged 79 died in Belgium.
A provisional UK record gust of up to 196 kilometres per hour was recorded at the Needles on the Isle of Wight.
At Mumbles Head near Swansea on the south Wales coast, gusts reached 140kph, while at North Wyke near Dartmoor in Devon, they hit 131kph.
Parts of London's O2 Arena roof were “ripped off” as Storm Eunice reached the capital.
Some of the white covering on the venue could be seen flapping in the strong winds in footage shared on social media. The famous building, formerly known as the Millennium Dome, hosts major events including concerts and features restaurants, bars, shops and a cinema.
The rupture led to about 1,000 people being removed from the venue and the cancellation of Friday night's scheduled Fugees gig.
The O2 wasn't the only building of note in the UK to be scythed by Storm Eunice's razor sharp winds. The Isle of Grain Power Station in Kent had one of its towering chimneys taken out.
The felling was confirmed by the power station's owner, Uniper Energy.
“An incident has occurred at Grain power station, during storm Eunice,” a representative for the firm said.
“We can confirm that there are no casualties and there is no risk to the local community.
“However, it has caused some damage on site and the power station has been temporarily taken offline as a precaution.”
The big clean-up could be hampered as yellow wind and ice warnings are in place across parts of the country.
Train networks were disrupted with flying debris, while there was damage to buildings and homes.
Footage shared online captured planes struggling to land in high winds and the spire of St Thomas Church in Wells, Somerset, crashing to the ground.
Storm Eunice prompts major incident declarations
A deluge of 999 calls in the London area led to emergency services declaring major incidents.
The London Fire Brigade said the declaration allowed it to focus its resources better.
South Central Ambulance Service was another to declare a critical incident.
“Declaring a critical incident allows us to seek further support from our partners and alerts the wider healthcare system to our existing challenges brought about by Storm Eunice in reaching patients as quickly as we would like,” said Paul Jefferies, assistant director of operations.
“We will continue to focus on reaching those patients with life-threatening or serious injuries and illnesses first, and unfortunately there will be unavoidable delays in getting to those patients with less urgent needs, for which we apologise in advance
Storm Eunice claims four victims in UK and Ireland
Four people have been confirmed killed by the storm. A woman in her 30s died after a tree fell on a car in Haringey, north London, on Friday afternoon, the Metropolitan Police said.
A man in his 50s died in Netherton, Merseyside, after debris struck the windscreen of a vehicle he was travelling in.
In Ireland, a man was killed while working on removing debris. The employee of Wexford County Council had been helping locals deal with the removal of a fallen tree in the north Wexford area.
The storm brewed in the central Atlantic and spun up from the Azores towards Europe driven by the jet stream blowing at 321kph. Extreme wind speeds could sow chaos along coasts and in exposed areas.
At least three other people across the UK have been taken to hospital with serious injuries linked to the storm.
Liz Bentley, chief executive of the Royal Meteorological Society, said the “sting jet” phenomenon means Eunice is particularly damaging.
“It's like it's the sting in the tail as the storm moves through and other people of almost depicted like a curling scorpion's tail in the cloud, having that kind of shape of a scorpion's tail with the sting on the end,” she said.
“Storm Eunice is one of those storms I think will go down in history. It'll be a case study for us as meteorologists, partly because of the strength of the wind.
“We'll be talking about this, I'm sure, for years to come.
Storm Eunice travel chaos
Travel across the UK by air, road, rail and sea has also been badly affected by Storm Eunice.
Passengers on easyJet flight EJU8014 from Bordeaux to London Gatwick endured two aborted landings before their plane was put in a holding pattern over the southern coast and then forced to return to the French city. It touched down back at its starting point more than three hours after it departed.
The Met Office warned flying debris from gusts of up to 144kph could result in danger to life, blow off roofs, uproot trees and close roads, disrupt train services and ground planes. A red warning is also in place for south-western England.
Such warnings are relatively rare. The most recent one in the UK was issued in November 2021.
The Port of Dover has announced it is temporarily closed to shipping due to Storm Eunice “in the interests of customer and staff safety".
Home Office minister Damian Hinds said the military would be available for any emergency operation but for now, people should take shelter.
“Please take precautions, please stay safe,” he said. “The weather is by nature unpredictable. We have only just had Storm Dudley and now Storm Eunice.
“It is unusual to have a red weather warning. It is very unusual to have two.
“I just encourage people to take the precautions they can.”