(CNN) -- Someday you may tell your grandchildren about the Blizzard of 2015.
The National Weather Service, which isn't prone to exaggeration, is using terms like "life-threatening" and "historic" to describe the weather system taking aim at the Northeast.
The first big storm of the year may drop up to 3 feet of snow on Boston and New York before it ends Tuesday, with freezing rain and strong wind gusts possibly reaching 55 to 65 mph. Blizzard and winter storm warnings have been issued from Maryland through Maine and into Canada.
"I want everyone to understand that we are facing -- most likely -- one of the largest snowstorms in the history of this city," said New York City Mayor Bill de Blasio.
That's saying something. The city's biggest snowstorm was 2006, when 26.9 inches of snow fell, followed by 25.8 inches in December 1947.
Spinning your wheels
More than 1,800 flights have been canceled for Monday and more than 1,600 for Tuesday, Flightaware.com reported.
The major U.S. airlines are offering fee-free rebooking of flights to and from the northeast on Monday and Tuesday. United Airlines has already canceled all Tuesday flights at Newark, LaGuardia and JFK, as well as Boston and Philadelphia, said company spokeswoman Mary Ryan said.
New York Gov. Andrew Cuomo urged commuters to work from home on Monday, if possible, because the roads will be treacherous. Main thoroughfares, including I-84 and the Long Island Expressway, may be closed during the evening commute and public transportation may be shut down.
Amtrak plans to operate a normal Monday schedule, but may re-evaluate later in the day.
Residents heeded the warnings and descended on stores like the King Kullen grocery in Valley Stream, Long Island, according to CNN affiliate WCBS. Some shoppers wondered if they were really prepared.
"I just got a call from my children's school that it was going to be canceled for Tuesday as well so now I'm, thinking it's bigger than I thought it was going to be," Patti Peretti said.
Hunker down for the long haul
The storm will come in waves, with New York, Boston and Philadelphia areas seeing light snow Monday morning and heavier snow in the afternoon, CNN meteorologists say.
The really heavy snow will begin Monday night and continue through Tuesday. Some areas will still be getting snow on Wednesday.
New York City Public Schools will be open Monday but all after-school activities and field trips have been canceled, according to the city government website. Schools will probably be closed Tuesday, the website said.
"My message to all New Yorkers is prepare for something worse than we have seen before," de Blasio said. "Don't underestimate this storm."
Some New York groups are already looking out for the most vulnerable residents.
Dorot, a nonprofit in New York, collected 475 bags of food and water supplies for homebound seniors, according to CNN affiliate WCBS.
"I think I'll use some of this, especially the soup," said Norma Amigo, 93, of the Upper West Side. "I will not go out if I think it's slippery out because I fell two weeks ago."
Cuomo directed all state agencies to prepare. New York has at least 1,806 plows and more than 126,000 tons of salt to spray on roads across the region. The National Guard will also have six dozen personnel and 20 vehicles stationed throughout the state Monday morning.
Decisions about Boston public school cancellations will be made Monday, the school system said on its Twitter page.
"Our city has been through blizzards before and I am confident we are prepared," Mayor Marty Walsh said in a statement on the city website. The city has 700 pieces of snow-moving equipment and 35,000 tons of salt ready, he said.
Christine Carew, a sales associate at Charles Street Supply in Boston, said customers have been coming into the hardware store since it opened Sunday to grab sleds, shovels, ice melt and snow brushes.
"This is kind of typical," she told CNN about Boston getting a lot of snow. "We're more prepared for it. We know it's going to happen."
Riding the storm out
On Plum Island, Massachusetts, Bob Connors said he'll try to ride out the storm, but will move to higher ground if thins get dicey, according to CNN affiliate WHDH. A 2013 storm destroyed homes on the island.
"When you're living on the edge of paradise like we are now, you give Mother Nature a lot of respect when we need to," said Connors.
Philadelphia could get 5-9 inches of snow on Monday and an additional 6-10- inches on Tuesday, the National Weather Service says. The School District of Philadelphia has already announced schools will be dismissed at noon Monday.
On Sunday, the National Weather Services upgraded its blizzard watch to a blizzard warning for the area from northern New Jersey through southern Connecticut, including New York City. Twenty to 30 inches of snow is possible with winds gusting 55 to 65 mph.
Visibility will be a major problem, said CNN meteorologist Judson Jones.
"This is not one of those storms you want to go out in while it's happening," Jones said. "You want to wait for the winds to die down ... before you go to the store."
Tuesday is shaping up to be a day when the reality of the weather really sets in.
One of the inevitable aftereffects of snow -- flooding -- will quickly become a problem.
There could be coastal flooding in Massachusetts starting early Tuesday with pockets of major flooding on east-facing coastlines, the state emergency agency said.
"Plan to work from home is the best advice for Tuesday," Jones said.