France's Atlantic seaboard was pummelled by the storm dubbed Xynthia, which unleashed gale force winds and torrential rains on Sunday, prompting the government to declare a national emergency.
The toll in France rose to 47 dead and at least 30 missing today and more than half a million homes were without power in the deadliest storm to have battered France since 1999, officials said.
At least four people died in neighbouring Germany, three in Spain, one in Portugal and one in Belgium.
More than 9,000 French firefighters and emergency workers backed by helicopters were deployed on Monday to try to reach stranded residents, mostly in the Vendee and Charente regions of western France.
Rescue teams took to boats to reach flooded houses whose residents were reported missing in the town of L'Aiguillon-sur-Mer. Hundreds of families slept overnight in shelters set up in schools and dance halls.
About 30 people were admitted to hospital, regional officials said.
President Nicolas Sarkozy was on Monday to visit the storm-battered coast, where eight-metre (26-foot) waves sent residents scurrying onto rooftops and the wind reached speeds of 150 kilometres per hour (93 mph).
Interior Minister Brice Hortefeux said the storm was particularly deadly because it hit at night.
"It's obvious that if this had happened during the day, the death toll would not have been disastrous, because people were taken by surprise during their sleep," Hortefeux said on France Info radio.
Resident Fabrice Petit du Bosquet said: "I managed with my girlfriend to climb on the roof, through the window because the water was rising fast. It was five o'clock in the morning."
"We tried to move our stuff up to to the mezzanine but then I decided that we should go on the roof. We had been waiting on the roof for one hour when we spotted our landlord in a boat and he helped us get out."
The European Union said it was ready to offer support for the countries affected by the storm and France said it would seek help to pay for recovery operations.
French farms and fisheries were hard hit and Agriculture Minister Bruno Le Marie promised compensation from a national disaster relief fund.
Some 500,000 homes were still without electricity on Monday morning after the storm caused a black-out in one million households, the ERDF electricity supplier said.
Commerce minister Herve Novelli said small businesses would receive 10,000 euros (14,000 dollars) in aid to help them cover the costs of repairs in storm-hit areas.
Air traffic began returning to normal at Paris Charles de Gaulle airport on Sunday evening, a spokesman said, after around a quarter of flights were cancelled during the day.
Winds of 175 kilometres per hour were recorded at the tip of the Eiffel Tower in Paris, but Xynthia fell short of the record 200-kph levels of a deadly 1999 storm system which killed 92 people.
Shortly after 5:00 pm yesterday, state forecaster Meteo France said the storm had passed into Germany, Belgium and The Netherlands, and there were reports of high winds in the Swiss Alps.
In Germany police said four people had been killed, most of them by falling trees.
In Spain authorities said Sunday that two men died when their car was hit by a falling tree while an 82-year-old woman was killed Saturday when a wall collapsed.
Portugal said Saturday that a 10-year-old boy was killed by a falling branch and flood waters continued to rise on Sunday.
Its northern cities of Porto and Vila Nova de Gaia issued flood warnings as the Douro river threatened to break its banks.
A man in his sixties was killed by a falling tree in Belgium, and emergency services were called out repeatedly to deal with fallen power lines.