BOSTON — A storm poised to dump up to 3 feet of snow from New York City to Boston and beyond beginning Friday could be one for the record books, forecasters warned, as residents scurried to stock up on food and water and road crews readied salt and sand.

Before the first snowflake had fallen, Boston, Providence, R.I., Hartford, Conn., and other towns and cities in New England and upstate New York towns canceled school Friday, and airlines scratched more than 3,700 flights through Saturday, with the disruptions from the blizzard certain to ripple across the U.S.

“This one doesn’t come along every day. This is going to be a dangerous winter storm,” said Alan Dunham, meteorologist for the National Weather Service in Taunton, Mass. “Wherever you need to get to, get there by Friday afternoon and don’t plan on leaving.”

The snow began falling Friday morning in some areas, with the heaviest amounts falling at night and into Saturday. Wind gusts could reach 75 mph. Widespread power failures were feared, along with flooding in coastal areas still recovering from Superstorm Sandy in October.

Boston could get up to 3 feet of snow, while New York City was expecting 10 to 12 inches. Mayor Michael Bloomberg said plows and 250,000 tons of salt were being put on standby. To the south, Philadelphia was looking at a possible 2 to 5 inches.

In the southeast Massachusetts town of Whitman, where up to 30 inches of snow is forecast, public works crews were clearing crosswalk signs, trash barrels and anything else that might impede plows later in the day.

“We’ve had instances where they have predicted something big and it’s petered out,” said Dennis Smith, a DPW worker. “I don’t think this is going to be one of those times.”

Smith’s partner, Bob Trumbull, sounded a note of optimism, saying the relative lack of snow earlier this winter would make this storm easier to clean up.

“At least there is room for this snow. There are no snow banks so we will have a place to put it,” Trumbull said.

Amtrak said its Northeast trains will stop running Friday afternoon. The organizers of New York’s Fashion Week — a closely watched series of fashion shows held under a big tent — said they will have extra crews to help with snow removal and will turn up the heat and add an extra layer to the venue.

Airlines have cancelled 3,775 flights in preparation for the Northeast storm, according to airline tracking website FlightAware. At New York City’s three main airports, most domestic carriers planned to cease operations between 2 p.m. and 5 p.m. Friday, resuming after noon on Saturday, FlightAware said. At Boston’s Logan and other New England airports, most airlines were to cease operations between noon and 4 p.m., and would restart Saturday afternoon.

Blizzard warnings were posted for parts of New Jersey and New York’s Long Island, as well as portions of Massachusetts, Rhode Island and Connecticut, including Hartford, New Haven, Conn., and Providence. The warnings extended into New Hampshire and Maine.

In New England, it could prove to be among the top 10 snowstorms in history, and perhaps even break Boston’s record of 27.6 inches, set in 2003, forecasters said. The last major snowfall in southern New England was well over a year ago — the Halloween storm of 2011.

Dunham said southern New England has seen less than half its normal snowfall this season, but “we’re going to catch up in a heck of a hurry.” He added: “Everybody’s going to get plastered with snow.”

At Stop & Shop supermarket in Mount Vernon, N.Y., on Friday morning, there was a line of shoppers outside when it opened at 7 a.m., and a steady stream followed. Checkout lines were long.

Mary Anne DiBello, 44, was stocking up her cart as the snow began to fall.

She said she hosted a sleepover Thursday night with four 9- and 10-year-olds, including her daughter.

“Now I think I’m going to be stuck with them until I bring them to school on Monday,” she said, adding her daughter just called her at the store to say the girls were awake.

“I told her, ‘Go wake your father.’ I’m stuck here.”

In New Hampshire, Dartmouth College student Evan Diamond and other members of the ski team were getting ready for races at the Ivy League school’s winter carnival.

“We’re pretty excited about it because this has been an unusual winter for us,” he said. “We’ve been going back and forth between having really solid cold snaps and then the rain washing everything away.”

But he said the snow might be too much of a good thing this weekend: “For skiing, we like to have a nice hard surface, so it will be kind of tough to get the hill ready.”

The governors of Connecticut and Massachusetts ordered nonessential state workers to stay home Friday and urged travelers to stay home.

Terrance Rodriguez, a doorman at a luxury apartment complex in Boston, took the forecast in stride.

“It’s just another day in Boston. It’s to be expected. We’re in a town where it’s going to snow,” he said. “It’s like doomsday prep. It doesn’t need to be. People just take it to the extreme.”