Around 10 million people were under winter weather alerts Monday in the Great Lakes and Northeast regions, where some residents may be waking up to a white Christmas.
"Much of the East Coast region will have a very cold start to the holiday week on Monday, with an arctic surface high slowly moving east across the region," the National Weather Service said in an advisory Monday.
Sunday was "the coldest morning of the season thus far" for many mid-Atlantic and Northeastern states, according to the weather service. Monday was also expected to be another frosty day but slightly milder compared with Sunday.
The Northeast was already treated to snow over the weekend, and it is forecast to get more. On Tuesday, there's potential for some light snow moving through New York City, while to the north, conditions are expected to worsen with a glaze of ice and 2 to 6 inches of snow possible from the Great Lakes to Maine.
Cities expected to be affected the most are New York, Boston, Chicago and Detroit.

But the question remains — can residents expect a white Christmas?
The prerequisite for a white Christmas is at least one inch on the ground, which is unlikely to happen in New York City, but some snow showers are possible elsewhere in the region the day of Christmas Eve. The heavier snow is expected in the interior Northeast and into Maine.
One thing Northeast and Midwest residents can expect for certain, though, is a cold Christmas, indeed.
Out in the West, "heavy rain and mountain snow" will return to the region Monday night, the weather service said.
"Although the storm system will be progressive overall, there will be a deep surge of moisture ahead of the cold front that will intersect the coastal terrain and the western slopes of the northern Sierra Nevada," the weather service said. "Rainfall totals on the order of 2-4 inches, and locally higher, are likely across this region through Tuesday evening."
Snow from this same storm system is expected to impact the most elevated areas in the central and northern Sierra Nevada, with up to a foot of snow possible.