The "Beast from the East", as the phenomenon has been dubbed by the British media, is expected to bring cold air from Russia over the next few days that will make it feel even chillier than thermometers indicate.
Rome saw its first snowfall since February 2012, with about three to four centimetres (1.2 to 1.6 inches) settling on the ground Sunday.
Schools were closed in the Italian capital as local authorities opened several train stations as emergency shelters for the homeless.
It was zero degrees Celsius (32 degrees Fahrenheit) in Rome on Monday morning, with a low of minus six Celsius forecast until Wednesday -- but no more snow is forecast.
In the north Italian city of Turin, heavy snow had caused a Serie A football game between Juventus and Atalanta to be postponed on Sunday.
Two people have died of the cold in Poland since Saturday, bringing the winter's toll to 48 since November, according to the centre for national security.
Temperatures plunged to minus 26.2 C overnight in the northeastern town of Goldap, with daytime forecasts predicting lows of up to minus 11 C on Monday in eastern Poland.
- Fears for homeless -
In France, where temperatures were forecast to drop to minus 10 degrees Celsius (14 degrees Fahrenheit) and feel as low as minus 18 C over the coming days, emergency shelters were opened for the homeless.
A homeless man in the city of Valence in the country's southeast was found dead on Sunday, after another man was found dead in his cabin in the suburbs of Paris on Friday. Both deaths were believed to have been linked to the cold.
Britain's weather service, the Met Office, issued a yellow weather warning no Monday and amber warnings for Tuesday and Wednesday, with more snow expected in eastern England.
"This week looks like being the coldest period we have had in the UK for a number of years," the Met said on Sunday.
"Parts of England and Wales are likely to see their coldest spell of weather since at least 2013 -- perhaps 1991," said Frank Saunders, the Met Office chief forecaster.
- Surf's up in Munich -
In Berlin, where at least 3,000 people are estimated to be living on the streets, overnight shelters for the homeless were 95 percent full, and overcrowding was feared in coming nights, as temperatures drop as low as minus 20 C, reported local public radio RBB.
Undeterred by the icy conditions, surfers in thick wetsuits rode Munich's famous continuous wave of the Isar River's Eisbach channel on Sunday morning, ZDF television showed.
Russia itself was not spared, with its meteorological service warning of "abnormally cold" temperatures of between minus 14 C during the day and minus 24 C overnight.
In Sweden, where the cold snap coincided with schools' winter sports break, most were happy to see the snow, with temperatures ranging from minus 5C in Stockholm to minus 20 C in the mountains near Ostersund, where many Swedes were spending ski holidays.
However, the snowfall did cause about 20 flights to be cancelled at Stockholm's Arlanda airport, primarily to European destinations, according to airport operator Swedavia.
In Slovenia, the motorway connecting capital Ljubljana and the port of Koper had to be closed near the coast due to the infamous "bora" winter wind that has been blowing with speeds of more than 100 kilometres per hour.
Special cross-country skiing courses were set up in parks in Vienna as temperatures dropped to as low as minus 20 C across Austria.
The Danube river had frozen over in some places, but Vienna authorities warned against skating, saying "there is a large probability that the ice will break". //AFP