The eastern United States braced for an arctic onslaught Monday, as forecasters predicted another blast of snow and cold in what already has been a merciless winter.

As many as 50 million people were in the path of the glacial weather, which will see temperatures far more frigid than normal, the National Weather Service warned.

"Numerous record low temperatures are expected!" the NWS said in a bulletin early Monday.

Snowfall amounts of six to 12 inches (15 centimeters to 30 centimeters) are anticipated in much of the mid-Atlantic, which includes Washington DC as well as New York City some 200 miles (350 kilometers) to the north.

US forecasters said the storm will buffet a wide swath of the eastern United States with snow, gale-force winds and brutal cold.

Unusually frigid cold was expected as far south as the Carolinas, which most years enjoy temperate winters with temperatures that seldom dip much below freezing.

"In addition to the widespread precipitation expected, the unusually cold weather is forecast to continue through much of the upcoming week for the eastern US, with temperature anomalies on the order of 20 to 30 degrees below average by mid-February standards," the NWS said.

Among the cities expected to be hardest hit by the temperature plunge are Erie, Pennsylvania, where thermometers are expected to fall to minus 28 degrees Celsius (minus 18.4 Fahrenheit) and Cleveland, Ohio, with minus 22 degrees Celsius (minus 7.6 degrees Fahrenheit).

The Flightaware air travel website said that some 1,500 flights had been cancelled by midday Monday, before the latest bout of inclement weather had been felt.

February has set a record as the snowiest month ever in Boston, with 10 times the snowfall it would get in a typical winter.

With the snowstorm expected to at least brush New England's most populous city, mountains of snow piling up in the city were likely to grow even higher.

"No end appears in sight as to the brutal winter we have experienced," the NWS wrote in its Boston forecast.

"This month will definitely be one for the record books in terms of snowfall and monthly average temperature," the NWS said.

Photos of the blanketed city showed snowplows clearing roads and tow trucks rescuing buried vehicles, while officials warned drivers to stay off the roads.