In its second day of extreme weather, Canada experienced some of its coldest conditions in Quebec City, with temperatures to hit minus 51 degrees Celsius with wind chill factor, due to 60 kilometer (37 miles) an hour icy winds.

In Montreal where the St. Lawrence was frozen over, the mercury hit minus 40, with Ottawa, at minus 45, enjoying the world's longest skating rink -- 7.8 kilometers (five miles) across the city.

Canadian automobile associations said emergency calls -- mostly related to cars not starting and frozen doors -- were flooding in, and ski stations had few customers.

Power firm Hydro Quebec, calling consumers to turn down the heating and cut off the washing machine at key hours to avoid an overcharge of its grid, saw its record of energy consumption beaten early Thursday to 35,601 megawatts.

And in the US North-East where the thermometer has been steady at between zero and minus 10 degrees for a week, worse was expected.

In New York, already covered by 10 centimeters of snow, bright sunshine and clear blue skies augured freezing lows of minus 28-31, according to the National Meteorological Service (NMS) which warned that frostbite could result in 30 minutes for exposed skin.

The NMS issued an alert for New Jersey, New York, Connecticut and Maine, with special warnings for New York City.

"The first shot of Arctic wind which arrived Tuesday evening has already produced wind chill values as low as 10 degrees below zero across the (New York) metropolitan area during the morning hours," the NMS said.

But with "a new round of reinforcing Arctic air" to pour into the region Thursday night, the weather service warned, the combination of temperatures of minus 15-17 degress mixed with north-west winds blowing at 32-40 kilometers (20-25 miles) will result in a dangerous wind chill factor of minus 28-31.

"City shelters are well prepared," said New York City Mayor Michael Bloomberg, anticipating temperatures too low for the homeless to remain outdoors. "Everyone wanting and needing a bed will get one -- without exception. Homeless outreach teams have been working out across the city, around the clock to convince individuals to come inside."

Daytime temperatures in Boston were at minus 20 degrees and were set to go lower in mountainous areas, with no signs of a let-up before the weekend.

TERRA.WIRE