Winter weather alerts stretched more than 1600 kilometres from Alabama to Maine, with the governors of Georgia, Virginia, North Carolina and South Carolina declaring emergencies due to the storm.
More than 200,000 homes and businesses in North Carolina, South Carolina, and Georgia reported power outages, according to website PowerOutage.US.
In North Carolina, where some regions saw record snowfalls, two people died on Sunday when they lost control of their car in Raleigh.
The highest snowfall totals were expected along the spine of the Appalachians as well as across the lower Great Lakes.
The storm made its way through the mid-Atlantic region towards New England on Sunday night, bringing snow that is expected to change to ice, sleet and eventually rain, the National Weather Service said.
In Canada, the storm is forecast to dump between 20 to 40 centimetres of snow through Monday morning over parts of southern and eastern Ontario, the Canadian province that shares part of its border with New York state, the government weather agency, Environment Canada, said.
The inclement weather hits just as Ontario schools were set to reopen for in-person classes on Monday after the winter break was extended because of the highly contagious Omicron coronavirus variant.
More than 3000 flights within, into or out of the United States were cancelled on Sunday, and more than 8000 flights were delayed, according to FlightAware data.
Toronto, home of Canada's busiest airport, is set to see accumulations of 15-20cm of snow.
This was a long weekend for most people in the United States as Monday is Martin Luther King Jr Day, a federal holiday.
Georgia Governor Brian Kemp said on Sunday people should avoid non-essential travel in areas affected by the storm.
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