Click through the gallery to see more photos from Winter Storm Niko in Boston.
As of late afternoon, New York's Hudson Valley and parts of Long Island had up to a foot of snow, while New York City recorded about 9 inches.
That fast-accumulating snow recalls conditions from a blizzard that hit the region in January 2016, a storm that left residents snowed in for days in outer borough neighborhoods that hadn't been plowed well - or at all.
Thus far this winter, Boston has had just over 15 inches of snowfall, about 10 inches below average at this point in the winter. Storm Team 4 breaks down the timeline here.
A doorman in New York City died after he fell through a window while shoveling snow, officials said.
Flakes started flying for most people around 7 a.m.
Near whiteout conditions are predicted for some areas, and at the height of the storm, snow could fall at a rate of two to four inches per hour.
"The last time we had a storm of this nature, accumulation turned out to be much higher than originally anticipated", Massachusetts Gov. Charlie Baker warned, saying forecasts were calling for 8 to 14 inches across the state.
While New Yorkers were basking in the sunny glory thinking spring had finally made a grand appearance, weather warnings were up everywhere regarding the arrival of a massive snow storm, the biggest for Northeast US this season.
Alternate side parking has been suspended on Thursday, February 9, but meters will still be in effect.
December 1947: The third largest blizzard in city history killed at least 77 people, with snow measuring at 26.8 inches in Central Park.
A report released in April 2016 from the nonprofit climate research and journalism group Climate Central found that across the USA, more than 40 percent of counties have had their biggest 2-day snow totals since 1980.
Governor Chris Christie in the state of New Jersey said state offices would be closed for all non-essential employees on Thursday.
Warming seas have put more water vapor into the air to fuel storms of all types, and warmer air holds more moisture as well.
A few inches of snow are on the ground to begin the morning, and there is a potential for snow showers throughout the day, according to the National Weather Service.
The storm is so rapidly intensifying with winds gusting to 45 miles per hour that it is "making air travel hard, if not impossible", the Capital Weather Gang reported.
Strongest winds will be over the South Shore and particularly over Cape Cod and the Islands with gusts peaking between 45-55 miles per hour during the evening on Thursday.
Conditions are expected to improve for the weekend. Unable to get around safely by vehicle and hampered by snowy sidewalks, some New Yorkers got creative. Blowing and drifting snow is expected.
The powerful, fast-moving storm blew into the MA area early Thursday, making the morning commute treacherous for thousands. Windy weather will make it feel even colder.
The winter storm is being caused by a southward plunge in the polar jet stream, causing a low-pressure system that's moving northeast, according to The Weather Channel.