A relentless winter storm brought Christmas Day danger and misery to millions of Americans as intense snow and frigid cold gripped parts of the eastern United States and raised weather-related deaths to at least 24.

A crisis situation was unfolding on Sunday in Buffalo in western New York, where a blizzard left the city marooned and prevented emergency services from reaching high-impact areas.

The Buffalo storm is “a crisis of epic proportion” and “the worst of the worst”, said New York Governor Kathy Hochul, a native of Buffalo, where 2.4-metre (8-foot) snow drifts against front doors and power outages in freezing temperatures have created life-threatening conditions.

More than 200,000 people across several eastern states woke up without power on Christmas morning, and many more had their holiday travel plans upended although the five-day-long storm featuring blizzard conditions and ferocious winds showed signs of easing.

The extreme weather sent wind chill temperatures in all 48 contiguous US states below freezing over the weekend, cancelled thousands of flights, stranded holiday travellers and trapped residents in ice- and snow-encrusted homes.

The two dozen weather-related deaths were confirmed across eight states, but some US media reported as many as 30 storm-linked fatalities, including four people in Colorado who likely died of exposure and at least seven in western New York.

In Canada, hundreds of thousands of people were left without power in Ontario and Quebec, many flights were canceled in major cities and train passenger service between Toronto and Ottawa was suspended.