Arctic blast hits Canada and US
Parts of Canada and the US have been getting their first blast of winter, sending temperatures plummeting by as much as 22C (40F) in days.
The sharply cooler temperatures are a result of frigid air pushed in by a powerful storm that hit Alaska with hurricane-force winds.
There have been more than two feet of snow in parts of Michigan.
And more than 150 flights were cancelled at the Minneapolis airport.
The chill is now spreading into the Pacific Northwest.
National Weather Service meteorologist Justin Titus said roads on the peninsula were in a "very poor condition" with two to three inches of snow falling an hour on Tuesday morning.
North America freeze
27C/48F drop in Alberta temperatures in past three days
33cm/13in snow fell in Wisconsin in first winter storm
22C/40F temperatures plunge below seasonal average
50 years since Calgary experienced a warmer October
In Minnesota, state police said at least two people were killed in accidents on icy roads.
Snowy roads were blamed for a Wisconsin school bus crash that sent two adults to hospital, according to a local broadcaster.
Terri Sommerfeld, a clerk at Ace Hardware in Webster, Wisconsin, said the store had sold six or seven snow-blowers in two days, the same amount they sell in a typical winter.
The National Weather Service said the snow should begin to ease on Wednesday.
What made this chill more of a shock was the way it struck so quickly after warm autumn weather.
David Phillips, a climatologist for Environment Canada, says Calgary experienced its warmest October for 50 years. The average temperature was 8.3C and it's usually 5.2C.
On Saturday afternoon, he said, Calgary was 14.4C but it dropped 32 degrees in the next 36 hours.