Heavy snow and unusually cold temperatures closed down airports, delayed trains and clogged roads across Europe Sunday, derailing travel plans for millions of passengers, including Canadians hoping to spend their holiday across the Atlantic or make it home for Christmas.

London's Heathrow Airport stopped accepting arrivals because of heavy snow on its runways, Frankfurt airport cancelled nearly half of its flights and Paris's Charles de Gaulle cut air traffic by 40 per cent.

The air travel chaos sent ripples across the Atlantic Sunday, causing headaches for Canadian passengers booked on flights to or from England or France.

Air Canada issued a statement warning customers flying to London to expect delays or cancellations and advising those travelling to Paris to expect long waits at best.

"Unfortunately, we do not anticipate resuming normal services at Heathrow for at least 48 hours," Air Canada CEO Duncan Dee said in a statement Sunday morning.

Dee also warned of a "tremendous backlog" once airports reopen and normal travel schedules resume.

The airline says it has revised its ticketing policy for affected customers to allow them to make alternative travel plans, space permitting, without any penalty.

Toronto native Rishi Patel, who is studying medicine in the U.K., had both his Saturday and Sunday flights home cancelled after waiting for hours at a crowded Heathrow airport.

His parents had to book him a first-class ticket to get him on a flight scheduled for Monday.

Patel described the scene at Heathrow as chaotic without a clear plan for getting passengers necessary information.

"It's getting to the point where it's just so ridiculous, you just don't know what to do," said Patel.

In Paris, heavy snow that has blanketed the French capital forced many passengers to spend the night sleeping at the airport in makeshift dormitories. The snow also cancelled a Lady Gaga concert because trucks carrying equipment for her show could not make it to Bercy stadium. The concert has been rescheduled for Tuesday.

Stranded travellers were also sleeping over at Amsterdam's airport and at Heathrow, Europe's busiest air traffic hub.

"The bars were open and some people were drinking and got quite nasty," passenger Sue Kerslake told the BBC.

Heathrow said no planes would land on its runways on Sunday and that only a small number of flights would be able to depart. Officials there blamed the airfield's closure on a significant build-up of ice on parking stands around the planes.

In Italy, Florence's airport was closed Sunday morning due to the snow and ice storms sweeping across Tuscany.

And Frankfurt airport, Germany's biggest, had cancelled more than 500 flights out of a planned total of 1,330 departures and arrivals.

While Frankfurt's runways were clear, flights were disrupted by problems elsewhere in Europe, with some passengers stuck there since Friday. Germany's Lufthansa cancelled several domestic and regional services to and from its main hub, though long-haul flights were little affected.

In Amsterdam, Schiphol spokesperson Mirjam Snoerwang said the airport's snow plows had cleared three runways, allowing some flights to take off. However, because of problems at other European airports, some 30 flights had been cancelled by late morning.

Rail services continued to face disruption as a result of the snow and drivers faced slow-going and kilometres-long backups of traffic -- an overturned tanker truck was causing long delays on the main M25 highway around London Sunday.

Icy conditions have been blamed for three deaths so far, British police said. A teenage girl was killed in a sledding accident, while a mother and her 10-year-old son died in a traffic crash.

The ice, snow and slush left cars skidding through streets in several French cities and forced the high-speed TGV trains to slow down considerably. Trains to Britain, Belgium and the Netherlands were also affected.

In Scandinavia, where temperatures in some places dipped to below -20 degrees Celsius, meteorologists warned snow was piling up on the icy roads following heavy snowfall and strong winds.

While airports were operating normally, several long-distance trains were delayed, and many commuter train departures around the city of Malmo in southern Sweden were cancelled.

With files from The Associated Press and The Canadian Press