Subfreezing temperatures will stretch all the way to the East Coast, where forecast low temperatures for Tuesday include 13 degrees in Boston, 18 in New York City and 12 in Washington, D.C.
Connecticut Gov. Dannel Malloy activated the state's severe cold weather protocol, mobilizing dozens of state agencies to respond to public safety and social services crises. Baltimore's health commissioner, meanwhile, issued a Code Blue alert opening shelters and the city's homeless services outreach network.
Even a large part of north Florida was under a freeze warning overnight, with Jacksonville expecting a low of 28 degrees, while Raleigh, North Carolina, was expected to hit 16 and Memphis, Tennessee, was predicted to hit 17.
And that's just the windup.
A second, separate system will quickly move in at midweek, this one carrying a lot of atmospheric moisture that means "we'll certainly be anticipating plowable snow in the mid-Atlantic into the Northeast," said Danielle Banks, a meteorologist for The Weather Channel.
The National Weather Service stressed that there's still "uncertainty given the fact that this is several days out," but it said conditions were shaping up for major winter storms in the Washington, D.C., Philadelphia and New York City areas late Friday through Saturday.
"I'm not ready at all," Megan O'Neill, who was shopping for supplies Monday in Lafayette Hill, outside Philadelphia, told NBC Philadelphia. "I would like the 60 degrees to continue for the rest of the winter."