The U.S. Northeast on Monday braced for a massive, crippling blizzard that could dump as much as 3 feet of snow as tens of millions of people were urged to stay home and airlines canceled thousands of flights.

Transit systems in New York, New Jersey, Connecticut and Massachusetts planned to curtail services, and several governors ordered motorists off roadways by evening in a region that is home to some 50 million people.

The National Weather Service issued a blizzard warning for New York City and surrounding areas between coastal New Jersey and Connecticut, beginning 1 p.m. EST (1800 GMT) on Monday and worsening overnight.