London (CNN) -- Eastern Europe shivered Tuesday in the coldest conditions seen this winter, with below-freezing temperatures and heavy snowfall leading to deaths, frostbite and widespread travel disruption.
Ukraine and Poland are among the worst affected countries, with lows in Kiev and Warsaw of -17 and -16 degrees Celsius (1 and 3 degrees Fahrenheit) respectively, far lower than the average for this time of year.
Ukraine's Emergency Situations Ministry said 30 people have died as a result of the cold since Friday. Twenty-one of the dead were homeless people, whose bodies were discovered on the streets, the ministry said, and four died in their homes.
The ministry said more than 600 people had sought treatment for frostbite and hypothermia over the past five days, with more than 500 of those treated in the hospital.
Thousands of people have sought refuge at government-run shelters as the temperatures have plummeted. About 1,590 heated tents operating across the country are offering warmth, tea and hot meals to those in need, officials said. Another 150 are due to be set up shortly.
Meanwhile, schools and colleges in Kiev have canceled classes until Monday because of the cold, city authorities said.
In Poland, the interior ministry urged people to look out for the elderly and homeless, saying temperatures were set to drop further as the week goes on, especially at night.
CNN meteorologist Mari Ramos said Romania and Bulgaria were among the first Eastern European nations to be affected by cold and heavy snow.
Tuesday morning saw lows of -22 degrees Celsius (-7 degrees Fahrenheit) in the Romanian capital, Bucharest, and -21 degrees Celsius (-5 degrees Fahrenheit ) in Moscow, compared with an average for the time of year of -3 degrees Celsius (25 degrees Fahrenheit) and -12 degrees Celsius (10 degrees Fahrenheit) respectively.
Those temperatures will feel even lower thanks to the wind. For example, the current temperature in Berlin is -6 degrees Celsius (21 degrees Fahrenheit) but feels like -14 degrees Celsius (6 degrees Fahrenheit) to the exposed skin, Ramos said, and hypothermia and frostbite can occur within just a few minutes if people are not properly dressed and protected.
In Slovakia, a 63-year-old man was found dead outside his house in the northern village of Sunava on Monday, the Slovak news agency SITA reported, saying temperatures in the region had dropped to -24 degrees Celsius (-11 degrees Fahrenheit).
In Serbia, one person has died and two are missing after heavy snowfall in the territory of Uzice, according to the state-run Serbian news agency Tanjug. Travel and electricity supplies have been disrupted, and a state of emergency has been declared in a number of districts.
State-owned Bulgarian National Radio said a record low of -29 degrees Celsius (-20 degrees Fahrenheit) had been reached in the northern town of Knezha early Tuesday.
Turkey was bearing the brunt of the snowfall as of Tuesday, with Greece, Albania, Macedonia also seeing heavy snow and below-freezing temperatures.
In Istanbul, all non-essential employees working for the city were given administrative leave, Turkey's semi-official Anatolian news agency reported. The snow is expected to continue through Thursday.
Very low temperatures are reported across Turkey, with heavy snow also expected in areas east of Marmara, central and eastern Black Sea coastal areas, the eastern Mediterranean coast and the east and southeastern parts of the country.
More than 780 villages nationwide have been cut off by heavy snow, Anatolian said. Major highways have also been affected, and much of the country is under a bad weather warning.
Istanbul's Ataturk International airport reopened Monday after snow caused the cancellation of more than 200 Turkish Airlines flights, some to international destinations.
The frigid air is set to move west across Europe and will stay in place through the end of the week, Ramos said, with heavy snowfall forecast for Tuscany and central Italy.
Twenty-three administrative areas in central and southern France have advisories due to snow and cold, while Paris will struggle to climb above freezing for its daytime highs for most of this week.
Temperatures in London will also hover near freezing, but while a few snowflakes dusted the city Tuesday, no significant snowfall is expected, Ramos said.
CNN's Talia Kayali, Theo Nikolaou and Laura Smith-Spark contributed to this report.