An arctic air mass settled over New York 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.

New Jersey Gov. Phil Murphy declared a state emergency for all 21 counties in the Garden State. A winter storm warning was in effect for 10 counties in the northern part of the state, where 6 to 8 inches (15 to 20 centimeters) of snow is expected to fall from Sunday afternoon through the late evening.