Snow began falling in New Jersey and New York on Sunday as the storm moved northward.
The National Weather Service said 30-60cm of snow was possible in many areas, along with heavy winds. Visibility in many areas was expected to be a 400 metres or less. Officials throughout the region urged residents to avoid travel.
"It's been a while since we've had a major nor'easter and major blizzard of this magnitude across the Northeast," said Cody Snell, a meteorologist at the service's Weather Prediction Center.
"This is definitely a major winter storm and a major impact for this part of the country."
The weather service issued blizzard warnings for New York City and Long Island, Boston and coastal communities in Delaware, Maryland, New Jersey, Connecticut, Rhode Island and Massachusetts.
State of emergency declarations were issued in New York City and other parts of New York state, New Jersey, Delaware, Rhode Island, Connecticut, Massachusetts as officials mobilised readiness efforts.
New York City Mayor Zohran Mamdani announced a ban on non-emergency travel on all streets from 9pm on Sunday until noon on Monday, with travel restrictions planned in New Jersey, Pennsylvania, Rhode Island and elsewhere in the region.
The emergency alerts, blasted to the phones of New York City residents, warned them to stay off roads "due to dangerous blizzard conditions".
Mamdani also cancelled in-person and virtual classes for city schools on Monday, calling it the "first old-school snow day since 2019".
"And to kids across New York City, you have a very serious mission if you choose to accept it: Stay cozy," he said.
Around the region, airports cancelled flights ahead of the storm, and even DoorDash announced it was suspending deliveries in the city overnight.
To the south, landmarks such as the Arlington National Cemetery in Washington, DC, announced closures on Monday.
The weather service said some of the heaviest snow was expected to fall overnight, with as much as five centimetres of snow per hour accumulating at times in some areas, before tapering off by Monday afternoon.
It said the storm's strong wind gusts could cause whiteout conditions and warned of a "Potentially Historic/Destructive Storm" southeast of the Boston-Providence corridor.
"Winds like that, combined with heavy, wet snow, are a recipe for damaged trees and prolonged power outages," said Bryce Williams, a meteorologist with the weather service's Boston office.
"That's what we're most concerned with, is the combination of those extreme snow amounts with that wind."
The storm could possibly meet the definition of a bomb cyclone, said Frank Pereira, another weather service meteorologist. That's when a storm drops at least 24 millibars in pressure in 24 hours.
"We're expecting it to drop by that magnitude at least over the course of the next 24 hours," Pereira said.
"I think when all is said and done, it will meet the definition of a bomb cyclone."
More than 3500 flights were cancelled across the US as of Sunday afternoon along with thousands of delays, according to the flight tracking website FlightAware.
