Northeast is reeling from the latest in a series of blizzards, with low temperatures exacerbated by strong winds.
A fourth major snowstorm in Boston, Massachusetts, made February the snowiest month in the city’s history.
Almost 2,000 flights have been cancelled so far, mostly from airports in Boston and New York.
The separate weather system developing in that area is expected to travel eastwards this week, bringing further snow and sub-zero temperatures to the north-east.
Nearly 2ft of snow was reported in parts of New England after the latest storm this weekend. Meanwhile, 13in of snow was recorded in Boston.
The bitingly cold weather in the north-east and Canada is expected to continue well into March.
This year, however, the jet stream has followed more of a north-south route, bringing Arctic air deeper into the US and Canada.
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