Just how cold is it in Canada? Ask the penguins at the Calgary zoo: Even they have had to take shelter.

King penguins - one of five species at the zoo in western Alberta province - are certainly accustomed to chilly weather, more so than species like the Humboldt that prefer somewhat warmer climes, said zoo curator Malu Celli.

But with a cold snap pushing temperatures below minus 30 degrees Celsius (-22F) on New Year's Eve - and feeling more like -40C in the wind - and with one five-month-old penguin chick still maturing, zoo officials decided to draw a line in the snow on Sunday, setting -25C as the birds' limit.

They brought the ten kings into their heated enclosure, where they can still be viewed by humans brave enough to be out.

Across Canada, planned New Year's Eve festivities in several cities were moved indoors amid a particularly brutal cold snap.

For nearly a week, most of Canada has been under an extreme cold alert.

At midday today, the country's coldest temperature was registered in Eureka, in northern Nunavut territory, at -40.5C.

The highest was in Prince Rupert, in the western province of British Colombia, at -7.5C.

People brave the cold temperatures in Quebec City

But Environment Canada promised "a gradual warming trend... (and) more seasonable temperatures by Tuesday."

It suggested dressing in warm layers "that you can remove if you get too warm" - a luxury penguins don't have.