NEW YORK -- A powerful nor’easter could bring blizzard conditions and more than a foot of snow to some parts of the Northeast, proving winter isn’t done yet.

The National Weather Service upgraded a blizzard watch to a blizzard warning for New York City from midnight Monday night through midnight Tuesday night for New York City, Long Island and parts of New Jersey and Connecticut, with snow amounts ranging from a foot to 20 inches and strong wind gusts.

New York Mayor Bill de Blasio urged residents to avoid unnecessary travel and help keep the roads clear for sanitation crews and first responders.

“We’re preparing for a significant storm on Tuesday, and New Yorkers should also prepare for snow and dangerous road conditions,” de Blasio said.

During a press conference Monday, de Blasio announced schools in the city would be closed on Tuesday.

Light snow is expected to begin late Monday night and intensify overnight into early Tuesday morning. The heaviest snowfall is expected Tuesday morning through the afternoon, with snowfall rates of as much as 2 to 4 inches per hour.

“This would certainly be the biggest snowstorm of the 2017 winter season in New York City,” said Faye Barthold, a weather service meteorologist based on Long Island.

New York Gov. Andrew Cuomo announced Sunday that the New York State Emergency Operations Center will be activated Monday evening, with stockpiles of sandbags, generators and pumps at the ready, reports CBS New York.

CBS News correspondent Kris van Cleave reports hundreds of flights have been canceled for Tuesday because of the storm and that number will climb. Chicago is seeing the bulk of the cancellations Monday, with flights between Washington and Boston expected to be affected on Tuesday. The airlines are still assessing their storm plans and expect this to be largely a one day event, but some delays and cancelations could linger into Wednesday in hard-hit areas.

It‘s estimated the storm could impact 50 million Northeasterners.

Long Islanders who spoke with the station seemed to be taking the forecast in stride.

The Saboni family, from Seaford, says they’re stocked up and ready for a storm they think is long overdue.

“I kind of expected this because of such a mild early winter,” husband Andy said, “but I was going to drag on until the spring possibly.”

His wife Judy says they have their salt and shovels ready to go.

Pat Myren and her friends from Long Island have loaded up their truck with supplies.

“I’m hoping, need to stay home and be safe and that’s what I’m praying for,” she said.

Boston also could get 12 to 18 inches, with isolated amounts of up to 2 feet across northeastern Massachusetts.

In Philadelphia, crews began treating some area roadways on Sunday. The city could see 6 to 12 inches of snow. The weather service said there is a chance the snow could change over to a wintry mix or rain for a time Tuesday morning, which could limit total snowfall amounts.

Farther south, in the nation’s capital, where the National Cherry Blossom Festival is scheduled to start Wednesday, snow accumulations of 6 to 10 inches are expected.

Winter’s last hurrah arrives just a week after the region saw temperatures climb into the 60s.

“It’s March its New England. You can’t trust the weather. The weather is made of betrayal in March, so we’re getting a nor’easter but I’d be happy, and that 50 degree weather last week was wonderful, but it’s March. What can you do?,” one man told CBS Boston.