The fourth significant snow storm in three weeks pounded the US Northeast on Wednesday, cancelling hundreds of flights and closing schools and federal offices on the second official day of spring.
Winter Storm Toby was expected to dump 10 to 18 inches (25 to 45 cm) of snow on New York, the US financial capital and country's largest city, home to 8.5 million people, as well as parts of New Jersey and Long Island before tapering off overnight.
The National Weather Service warned against wind guests of 45 mph (72 kph), advising that power outages and downed trees were possible in New York, New Jersey and Connecticut.
In the federal capital Washington, where three to eight inches of the white stuff was expected, schools closed and federal government offices went into shutdown.
Congress, however, was operating with lawmakers scrambling to agree on a federal spending bill to stave off a government shutdown.
The Federal Reserve also said it was continuing "as planned" a meeting widely expected to lead to the first of at least three interest rate hikes this year as the central bank works to head off inflation.
Nearly 4,000 flights within, into or out of the United States were cancelled, including a majority at Newark and LaGuardia, two of New York's three area airports, and nearly half at John F. Kennedy International and Philadelphia's airport.
More than a third of flights were cancelled at Washington's Reagan National Airport, the flight aware website added.
New York Mayor Bill de Blasio warned residents to stay off the roads and stay home if possible, with the snow expected to intensify through the afternoon and night, hampering the evening commute.
In New Jersey, Governor Phil Murphy declared a state of emergency and schools closed in Philadelphia. New Jersey Transit, the commuter rail service, said it was implementing a severe weather rail schedule.
Boston, where winters are more severe than further south, was expected to be worst hit at the end of the day with flooding a risk in coastal areas.