Hundreds of thousands of airline passengers will be grounded this weekend as Hurricane Irene sweeps up the East Coast, past some of the nation’s busiest airports.

JetBlue Airways said Friday it was scrubbing about 880 flights between Saturday and Monday, most of them to and from hub airports in New York and Boston.

American Airlines canceled 32 flights on Friday, mostly in North Carolina and Virginia, and expected to halt flights in and out of Washington-area airports — about 150 flights a day — around noon Saturday. Southwest Airlines planned to stop flights to and from Norfolk, Va., beginning Saturday morning.

Irene is expected to make landfall around North Carolina on Saturday, move up the coast to New York on Sunday and then weaken as it plods through New England. It could strike major airports from Washington to Boston.

“You’re affecting all the major airports on the northeastern seaboard,” said David Swierenga, a former chief economist at the Air Transport Association trade group who now runs consultant AeroEcon in Round Rock, Texas. “The number of flights that they have at those airports per day is very high. I expect this will be a major disruption.”

The JetBlue cancellations are likely just the tip of the iceberg. Other airlines said Friday they were waiting to be more certain about Irene’s path before announcing more cancelations.

Airlines waived rebooking fees for customers who wanted to delay their flights to more than two dozen cities on the East Coast. Details varied by airline, with some giving travelers more time to make their rescheduled flight. Travelers whose flights were canceled would be eligible for refunds.

George Hobica, founder of the travel website airfarewatchdog.com, said travelers who bought nonrefundable tickets should wait until the airline cancels the flight rather than taking the airlines’ offer to reschedule by a few days.

The problem with rebooking on the airlines’ terms, Hobica said, is that you’re unlikely to want to take the same trip a few days later.

Projected costs from air-traffic interruptions are among those used by Kinetic Analysis Corp. in estimating $20 billion in overall economic losses from Irene, including missed work time, power failures and shipping disruptions. The firm forecast $13.9 billion in insured losses.

Delta and JetBlue Airways Corp. have hubs at New York’s Kennedy airport, and United’s Continental Airlines flies from New Jersey’s Newark Liberty. Together with New York’s LaGuardia, the three airports form the busiest U.S. aviation market.

Sandwiching that airspace is Philadelphia, where US Airways Group Inc. has a hub and Southwest Airlines Co. is the second- biggest operator; Washington, home to United’s hub at Dulles airport and a US Airways base at Ronald Reagan National; and Boston, where JetBlue is the largest tenant.

Delays in the area can ripple across the entire U.S. air- traffic control system.

Irene may also affect trans-Atlantic routes as well. American and joint-venture partner British Airways began hourly London departures from Kennedy each evening this year.

FedEx Corp., operator of the world’s largest cargo airline, and United Parcel Service Inc., the biggest package-delivery company, were monitoring their East Coast air and ground operations to decide on storm preparations, spokesmen said yesterday.

The Northeast’s concentration of airport hubs makes Irene a bigger threat for cancellations than a storm striking the southeast U.S. or states adjoining the Gulf of Mexico, where hurricanes are common.

Those regions have only two hubs near the coast, Continental’s in Houston and American’s in Miami. New Orleans, ravaged by Hurricane Katrina in 2005, was only the 43rd-busiest U.S. airport by departing passengers in the year ended in May, according to the Bureau of Transportation Statistics.

Winds and rain may not be airlines’ only challenge from Irene. Power failures, common in hurricanes, also may keep airline employees from getting to airports to restart service once the worst of the storm passes, said Mann, the consultant.

Planes also are flying with record numbers of full seats, especially at the end of the U.S. summer vacation season, making it difficult to find new seats for passengers on grounded flights after the storm moves through.

“We’re at a peak of a peak month, right before the Labor Day holiday, which will make it very difficult to reaccommodate customers on canceled flights,” Mann said.