McCrory urged North Carolinians to stay indoors -- even if it meant sleeping at work -- rather than risk the treacherous roads.
"If you're in a safe warm place, stay in a safe warm place," McCrory told CNN.
"We've already had two fatalities and we don't want to see more."
Specialty website FlightAware said airlines canceled at least 3,700 flights on Wednesday while a further 6,500 had been scrapped on Thursday, including many to and from New York, Atlanta, Philadelphia and Washington.
Downtown Washington was a virtual ghost town. Most buses were not running and subway cars were nearly empty.
As the snow started blowing in overnight, temperatures hovered around 26 degrees Fahrenheit (minus three Centigrade) but the bracing winds making it feel more like 15 degrees, forecasters said.
The White House cancelled its daily news briefing, and federal agencies told workers to stay home.
The Federal Emergency Management Agency said it was in contact with state emergency offices in densely populated Maryland, Pennsylvania and Virginia to assess their assistance needs as the storm builds.