A blizzard warning remains in effect across New Jersey, New York City and Connecticut through Monday evening, with the monster storm marking the first blizzard warning for New York City in nine years.

A blizzard warning is also in effect in Boston, Rhode Island and some of the Maine coast through Tuesday morning.

Powerful winds could reach 55 mph in New York City and 75 mph in Boston. Wind gusts have reached 84 mph on Long Island and 73 mph on Cape Cod, Massachusetts.

The heavy snow and winds will be strongest in the morning and then weaken in the afternoon across New Jersey and New York City. In the afternoon, the snow will continue in Rhode Island, Boston and the Maine coast before tapering off in the evening.

But when the snow lightens up, the winds will still be very strong, reducing visibility Monday night.

Storm totals are on track to reach 1 to 2 feet across much of the Northeast. New York City and Boston could see 20 inches; New York’s Long Island could see 2 feet; and New Jersey and Philadelphia are forecast to get 11 to 15 inches.

Coastal flooding is also a major concern along the coast from Virginia up to Boston. Parts of Long Island could see more than 2 feet of flood inundation.

-ABC News’ Kenton Gewecke

More than 5,000 flights have been canceled within, into or out of the U.S. on Monday, with airports in New York City, New Jersey, Boston and Philadelphia hit the hardest.

While those airports remain open, travelers are advised to check their flight status before heading out the door.

The winter storm continues to rapidly intensify off the coast of Virginia and North Carolina, now producing heavy snow and gusty winds from Virginia Beach to Philadelphia to New York City to Newport, Rhode Island.

Heavy bands of snow are producing 1-3 inches per hour of snow fall have been observed and are expected to continue over the next few hours, particularly into the morning from New Jersey and New York City out to Long Island, as well as to Hartford, Connecticut, and Providence, Rhode Island.

Some bands have been strong enough to produce lightning and thundersnow, too, over the past couple of hours. There have been some reports of thundersnow in Long Branch, New Jersey, and briefly in New York City. We could continue to see that with the heaviest bands through this morning along the coast from Virginia to the Jersey Shore and Long Island to coastal New England.

Visibilities have dropped to less than a half mile at New York City’s Central Park, with wind gusts between 20 and 33 mph being reported through the overnight hours. While New York City has not yet reached blizzard conditions -- which require gusts of 35 mph, visibilities down to 1/4 mile or less, all for at least three consecutive hours -- they are seeing near-whiteout conditions leading to reduced visibilities.

As of 12 a.m. ET, the center of the storm measured a pressure of 980 mb. At 12 p.m. ET Sunday, the center of the storm had measured a pressure of 1,005 mb. This means that within the span of 12 hours, the center of the storm dropped 25 mb in pressure and surpassed the criteria of "bombogenesis" -- a pressure drop of at least 24 mb within 24 hours.

The storm is expected to continue rapidly intensifying over the next few hours and the center of the storm will continue to deepen, allowing for stronger wind gusts and heavier snow bands with the nor'easter through this morning.

-ABC News' Kyle Reiman

As of 9 p.m. on Sunday night, more than 21,000 customers were without power in New Jersey, and more than 12,000 customers were without power in Virginia.

-ABC News' Kyle Reiman