More than 7,000 flights were behind schedule yesterday night, many of those in New York, Washington and Chicago as people struggled to travel before Christmas.
At least 11 people in the US have been killed in the storm.
In Canada, police said two people in Ontario are dead from carbon monoxide poisoning after using a gas generator to heat their blacked-out home northeast of Toronto.
The region was under a cold alert, with temperatures expected to be well below freezing today.
Some US states kept emergency shelters open for people who would be without power.