The death toll from a bitter cold spell across Europe increased to at least 40, officials said on Friday, while some of the worst floods in a century devastated parts of the Balkans.

In many parts of Europe, train services continued to see heavy disruptions due to icy tracks, but air traffic was returning to normal in many places. Britain’s Gatwick Airport reopened after heavy snowfall forced a 48-hour closure, though its website warned of delays and cancellations as freezing temperatures persisted. London’s Heathrow Airport was operating, but 45 arrivals and 25 departures were canceled.

The Charles de Gaulle airport in Paris was again operating normally but many areas of France faced traffic problems due to the snow.

In Warsaw, police reported 12 deaths overnight, raising the death toll in Poland alone to 30 over the past three days. In the Czech Republic, the death toll rose to four after a man was found frozen in Prague. In Germany, three people have now been killed, while authorities in northern England said they had found the bodies of two elderly residents of Cumbria this week who are believed to have frozen to death.

Many of those who died in Poland are drunks or homeless people and police canvassed the streets in the hopes of preventing more from freezing to death, repeating appeals to Poles to report any homeless people they come across. Temperatures across most of Poland were around —15 C (5 F) in the night but rose several degrees during the day on Friday, warming from a lows that dipped —20 C (—4 F) earlier in the week.

It’s “an early start to the winter because we are still in the autumn season,” said Omar Baddour, a scientist with the World Meteorological Organization in Geneva. “It’s not very, very unusual, but it is an extreme winter spell that is going to last a few days.”

Dr. Baddour said that the cold comes from winds pushing an Arctic chill over the continent, a pattern also seen during last year’s long and frigid winter. But he said it’s too soon to say what in store for the continent this year.

Authorities, meanwhile, declared a state of emergency in three Balkan countries, Bosnia, Serbia and Montenegro, and evacuated hundreds of people after heavy rainfall caused severe flooding along the Drina River, the worst in 104 years. But floodwaters receded significantly overnight in Bosnia, leaving a trail of mud and debris in many areas.

Bosnian authorities used rafts to rescue people on Thursday from apartments in Foca, and on the other side of the river, hundreds of people were evacuated in Serbia and Montenegro as the Drina flooded farms and roads. Schools were closed, many people had no electricity or heat, and water supplies were contaminated along the river in all three countries.

In Montenegro, rivers have totally submerged entire villages. Interior Minister Ivan Brajovic described the floods as “unprecedented” while the “Pobjeda” daily compared the country to Bangladesh.

Thousands of people and livestock were also evacuated from northwestern Albania after severe floods. A state of emergency was declared in the city of Shkodra, which remains isolated from the rest of the country by days of heavy rain.

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