Heavy snow is expected to blanket large portions of the Eastern U.S. while much of the country will endure dangerously cold temperatures in the coming days.

An arctic air mass settled over City and much of the country Sunday evening, bringing a deep freeze and the chance of more snow than the city has seen in three years.

Snow was falling in the Mid-Atlantic and New York City on Sunday. The coldest air in several years will descend across much of the country starting Monday, forecasters said.