Extremely cold, dense air has enveloped a wide swath of Saskatchewan and Manitoba, as well as parts of northeastern Alberta, and will be descending upon much of the U.S. Midwest today.
Over the next couple of days, the polar air will even reach as far south as the Gulf Coast, and also east to southern Ontario and the U.S. Northeast.
Wind chill warnings are also in effect for northwestern Ontario, as another blast of Arctic air invaded the region Saturday night. Temperatures are expected to plummet to –30 C to –35 C. With wind chills, it will feel more like –40 C Saturday night and into Sunday morning.
Much of Saskatchewan and Manitoba are under extreme wind chill warnings, where residents are shivering through temperatures in the -40s — feeling closer to -50 C in the wind.
The potentially record-low temps are heightening fears of frostbite and hypothermia.
The deep freeze in the Prairies is nothing new to residents of Winnipeg who have been hearing about frostbite warnings for four weeks now. The kind of cold people are experiencing can freeze skin in under 10 minutes.
One of the coldest places in Canada on Saturday night was Newfoundland, which was hit with a strong blizzard Friday, followed by temperatures reaching -30 C with the wind chill.
St. John's Mayor Dennis O'Keefe said Sunday he is recommending that schools and post-secondary institutions be kept closed until at least Wednesday.
"It gives us, as a city, time to get out there and deal with the streets and deal as much as we can within the next few days with sidewalks and everything else," he said.
He also recommended that people help out by "shovelling out the catch basins" as the province is due for heavy rain and warmer temperatures.
"That brings another challenge," O'Keefe told CBC News in an interview Sunday afternoon. "Whether there will be possible flooding in neighbourhoods."
O'Keefe also said he's worried about the swing in temperatures and mixed precipitation which could load down the transmission lines with ice and trigger another round of massive outages.
Hundreds of thousands of people were already left without power following a fire at a substation when the blizzard hit Friday.
"The good news is that it's warmed up quite a bit," said the CBC's Peter Cowan in St. John's on Sunday morning.
"Fortunately, a lot of people woke up with power ... [and] because a lot of homes have been without power for up to 30 hours, their homes often blow a fuse because everything starts powering up again."
While the provincial utility said it made a lot of progress overnight to restore power, some customers could be left in the dark and cold until Tuesday. About 35,000 Newfoundland Power customers remained without electricity on Sunday morning. About 190,000 had lost power at the height of the outage on Saturday.
Newfoundland and Labrador Premier Kathy Dunderdale said Sunday her government will be asking large consumers of energy to conserve power to close or reduce operations over the next few days as energy conservation will be paramount.
Newfoundland Power said 60-minute rolling outages are now taking place to conserve power as the system load grows.
"With the lows we've had and everyone relying on electric heaters, the system has not been able to keep up with that demand," Cowan said. "So, they have to try to spread out that demand."
Several flights were cancelled in St. John's and the city announced it was opening a warming centre after roughly half the island lost power. Other municipalities opened public buildings for people needing warmth as some coped with digging out from as much as 40 centimetres of snow.
Flash-freeze' for parts of Central Canada
Elsewhere in the country, people in southern Ontario are bracing for another snow storm. Snow is already falling in some areas but it is expected to intensify later in the day and into Sunday night.
Some areas will be hit with mixed precipitation. Toronto and the Ottawa region are under a freezing rain warning. Areas northwest of both cities could see anywhere from 10 to 20 centimetres of snow.
CBC Meteorologist Janine Baijnath warned of a "flash-freeze" in the Toronto area in the wake of freezing rain, which could cause transportation problems among other things.
A freezing rain has also been issued for most of eastern Ontario for Sunday evening and into Monday morning.
Across much of Quebec, the extreme cold has given way to warmer temperatures. However, now there is a freezing rain warning in effect for the southern and central parts of the province just as many people get back on the road at the end of the holiday season.
South of the border, bitterly cold temperatures blowing into the U.S. Midwest and Northeast in the coming days are likely to set records.
About 1,200 flights had been cancelled Sunday at O'Hare and Midway international airports in Chicago, aviation officials said, and there also were cancellations at Logan International Airport in Boston and Tennessee's Memphis and Nashville international airports.
The frigid air began Sunday and was expected last for at least two more days. The cold mass of air could be funnelled as far south as the Gulf Coast because of what one meteorologist called a "polar vortex," a counterclockwise-rotating pool of cold, dense air.