Double-digit sub-zero temperatures have claimed more than 30 lives over the past few days, many of them migrants or homeless people found frozen to death.
Sunday was the deadliest day this winter for cold-related deaths in Poland, where temperatures have plunged to below minus 20 degrees Celsius (minus 4 Fahrenheit) in some regions.
"Yesterday, 10 people died of cold," Poland's centre for national security (RCB) said Monday in a statement, adding that "the number of hypothermia victims has reached 65," since November 1.
Heavy snowfall in Turkey's main city Istanbul paralysed traffic for a third straight day with the Bosphorus Strait closed to ships and hundreds of flights cancelled.
Ferry services between the European and Asian sides of the city were scrapped and schools across the city closed.
Flagship carrier Turkish Airlines said only 292 departures from Istanbul's Ataturk Airport were expected on Monday.
On a normal day, the airport can accommodate over 1,500 landings and take-offs.
Turkish Airlines CEO Bilal Eksi said more than 600 flights had been cancelled on Sunday and over 10,000 travellers unable to reach Istanbul had been put up in hotels worldwide.
A 68-year-old homeless man was found frozen to death in the Macedonian capital Skopje while in Serbia, the southeastern town of Sjenica saw the mercury plunge to -33 degrees Celsius.
- 'Nobody is helping us ' -
Traffic on the Danube and Sava rivers was halted in Serbia. Scores of migrants in the capital Belgrade took shelter in a warehouse near the railway station, spurning shelters provided by the government for fear they would be deported back to their countries.
"It's very difficult, especially at night," said Niamat, a 13-year-old Afghan. The temperature overnight was -15 degrees Celsius.
"I have been waiting here for three months and I do not know when I will be able to continue my journey," said the young migrant, who is travelling alone.
Ismail, aged 16, added: "Nobody is helping us, it's very cold and I'm worried how we will endure this."
Schools were closed across cities in central Siberia on Monday but classes resumed in Moscow where the temperature rose by seven degrees to -20 degrees Celsius.
The Russian capital recorded its coldest Orthodox Christmas Night for 120 years at the weekend, according to media reports.
Greece and Italy have also seen fierce cold weather over the past week and in both countries, several migrants have died of hypothermia.
With more than 60,000 mainly Syrian refugees on its territory, Greece has moved many migrants to prefabricated houses and heated tents.