HALIFAX—Extreme cold weather alerts remain in place today for the Atlantic provinces and northern regions of Quebec and Ontario due to frigid temperatures brought on by an immense Arctic air mass.

The alerts issued by Environment Canada for the second day in a row affect six provinces from Ontario to Newfoundland and Labrador, as well as communities in Nunavut and the Northwest Territories.

The onset of the freezing conditions on Friday sent cities, towns, governments and private agencies scrambling to provide shelter for vulnerable people as the wind makes temperatures feel like −40 C to −50 C in some areas.

In such conditions, frostbite can develop in minutes on exposed skin.

The cold alerts remain in place for all of New Brunswick, Nova Scotia and Prince Edward Island, as well as the majority of Newfoundland and Labrador.

Temperatures have risen slightly in Ontario and Quebec, where alerts now only affect northern regions of both provinces.