Nearly 300,000 homes have been left without power in Britain and France, and trains and planes cancelled as a fierce storm battered the region, leaving at least two people dead.
A 17-year-old girl died after a tree fell on to the static caravan where she was sleeping in Hever, southeast England, and a man in his 50s died when a tree fell on his car in Watford, north of London, police said.
The rough conditions at sea forced rescuers to suspend the search for a 14-year-old boy who was washed out to sea from a beach in East Sussex on England's south coast on Sunday.
More than 450 people were stranded for several hours on two ferries outside the port of Dover after it was closed to sea traffic, as huge waves lashed the coastline on both sides of the Channel.
Winds reached 99 miles per hour (159 kilometres per hour) on the Isle of Wight off the southern English coast, according to Britain's Met Office national weather centre.
Heavy rain and winds of 80 mph elsewhere brought down hundreds of trees, while a crane fell onto the roof of a government building in central London. Police said nobody was hurt in that incident.
The Energy Networks Association, an industry body, said 220,000 homes across Britain were without power, as electricity lines were knocked down across the country.
In northern France the storm left some 65,000 homes without power early on Monday, according to the ERDF distribution network, after wind gusts reached 139 kilometres per hour. Earlier ERDF had estimated 75,000 homes were affected.
Southern England bore the brunt of the storm, with train operators cancelling services across the region in anticipation.
Many commuters delayed their journeys until it passed, leaving central London stations eerily quiet during what normally would have been the rush hour.
The capital's Heathrow airport cancelled 130 flights, about 10 per cent, while delays were reported on the Eurostar cross-Channel train service due to speed restrictions.
Meanwhile more than 30 firefighters were deployed to a gas explosion in Hounslow, west London, after a falling tree caused a gas main to rupture. Three houses collapsed and two others were damaged, the fire service said.
"Clearly this has been a difficult night for many Londoners and continues to be an incredibly trying morning," said Mayor of London Boris Johnson.
He said transport and emergency services were "working flat out in an effort to keep London moving and minimise disruption as far as is possible." Several major bridges were also closed, including the Severn Bridge over the estuary between England and Wales.
The Met Office said 50 millimetres (almost two inches) of rain fell in some areas overnight as the storm tracked eastwards across Britain.
The Environment Agency issued 133 flood alerts and warned that flooding was likely across 12 areas of southwest England, including Devon and Cornwall.
The storm, named St Jude in Britain after the patron saint of lost causes whose feast day was on Monday, had earlier been predicted to be the worst for a decade.
Forecaster Helen Chivers had told AFP the expected damage was likely to be comparable with a storm seen in October 2002, although stronger winds have been recorded since then.
However, the devastation fell far short of that caused by the "Great Storm" of October 1987, which left 18 people dead in Britain and four in France and caused damage worth 1 billion ($1.6 billion or 1.2 billion euros at current exchange rates).
The Met Office had given plenty of warning of St Jude - in contrast to 1987 when BBC weatherman Michael Fish famously assured viewers just hours beforehand that no hurricane winds were expected.
The storm also disrupted life in The Netherlands. A woman was reported dead in the town of Gracht after being hit by a felled tree. Another person died after a tree hit a car.
Public officials said high winds were hampering large parts of daily Dutch life. People were being urged to stay indoors and many flights had been cancelled.
A ferry from Newcastle in Britain with 1000 passengers could not dock at Ijmuiden as planned, leaving the ship to ride out the storm on the water.
However, ferry service between Dover and Calais had been resumed after an interruption.