The winter storm that snarled thousands of flights and disrupted air travelers the day after Christmas continued to cause cancellations and delays here and at airports along the Eastern Seaboard on Monday.

At Philadelphia International Airport, 600 departing and arriving flights were canceled Monday as the ripple effect of the snowfall bogged down travel plans, even to destinations under sunny skies.

Jim and Mary Beth Ferrie and sons Jonathan, 22, and Brendan, 19, from Sparta, N.J., spent a second day trying to get to New Orleans to begin a cruise to Belize and Cozumel that was to leave at 4 p.m. Monday.

After their flight Sunday from Newark was scrubbed, the family - joined by friends from Scotch Plains, N.J. - drove to Philadelphia and rebooked on an 11 a.m. US Airways Group Inc. flight to New Orleans. But that was canceled, too.

"We were at the gate, 45 minutes from boarding, and they canceled the flight," said a frustrated Mary Beth Ferrie. "We are trying to find another flight. This is like Chevy Chase's Christmas vacation."

On Monday night, incoming flights were delayed an average of 2 hours, 59 minutes, the Federal Aviation Administration said on its website.

The air-travel picture for Tuesday and beyond is unclear.

"We haven't gotten any estimates from the airlines," airport spokeswoman Victoria Lupica said. "The airlines' goal was to get back to normal operations and continue that Tuesday."

Much depends on several of the large airports in the Mid-Atlantic area, such as JFK and LaGuardia in New York, Newark Liberty, and Boston's Logan Airport. All were hit harder than Philadelphia International by the storm that began Sunday afternoon, and the weather's ill effects lingered in pronounced ways Monday.

Philadelphia's airport had a foot of snow but never closed, Lupica said. About 1,200 passengers stayed overnight Sunday inside the airport and were given blankets, pillows, bottled water, juice, and cookies.

Among those who napped on a chair was Marius Roth, 21, from Switzerland. He said his flight from Los Angeles was late arriving Sunday, and he missed a scheduled 6:10 p.m. flight to Zurich. Roth was hoping to fly standby Monday evening. "The flight is full, but if somebody misses the plane I'll get on," he said.

Airlines canceled 397 flights Sunday out of 520 at Philadelphia airport, Lupica said.

More flights - 600 - were canceled Monday than Sunday, including 209 early-morning flights. There were fewer cancellations Sunday because the storm did not hit until the afternoon. Gusting winds Monday caused US Airways to cancel some flights by smaller, regional jets.

US Airways canceled 763 flights, mainline and express, Monday, many of them into and out of New York, Philadelphia, and Boston, spokeswoman Valerie Wunder said. It has canceled 58 flights for Tuesday.

"We are waiting for New York airports to reopen," Wunder said. Newark had one runway open late Monday. JFK opened at 6 p.m., and LaGuardia was to reopen last night.

Southwest Airlines Co., Philadelphia's second-busiest carrier, cut 250 flights Monday out of 6,200 across its network. Southwest was operating and digging out at all airports where it operates, except LaGuardia and MacArthur Airport on Long Island, spokesman Paul Flaningan said.

Philadelphia International was open throughout the storm, with one primary east-west runway always in operation. About noon Monday, both primary runways were open, and by late afternoon, all four runways were operational, Lupica said.

Airport concessionaires and shops "loved the storm. This is their favorite time of year," said James Tyrrell, deputy director of airport properties. Three restaurants, Au Bon Pain, Jet Rock, and Chickie's & Pete's, stayed open all night Sunday, and others were open as late as 1 a.m. to accommodate stranded passengers.

US Airways, Philadelphia's dominant airline with an international hub here, continued flying after the storm hit to get passengers who had been stranded in Europe back to the United States, Tyrrell said.

"The problem was, by the time the trans-Atlantic flights got in, the domestic connections were already canceled," he said. "So passengers could not get out Sunday night. That was the reason we had so many stranded passengers."

Lutty Ramos flew with his wife and 8-month-old daughter from Puerto Rico on Sunday, but their next flight, to Columbus, Ohio, was canceled. They spent the night in a nearby motel.

Stranded travelers and aircrews filled airport hotels Sunday night.

"We have plenty of them," said Harry Sandhu, manager of the Microtel Inns & Suites. He estimated that he rented 50 rooms to 70 people because of the storm.

The Skyview Plaza Hotel & Suites rented 150 rooms to snowbound travelers, and the majority of the Embassy Suites Hotel was filled with guests whose flights never got off the ground, front-desk personnel said.

Center City hotels gained storm-related business as well, though not just from the airport. Johny Hoff, a front-desk agent at the Doubletree Hotel on South Broad Street, said the hotel had "maybe 40 stranded travelers altogether," including people who intended to travel by car and train. On the other hand, Hoff said, "there were a lot of cancellations because of the Eagles game."

Sarah Avayou and Richard Larson arrived at the airport Monday to learn that their flight home to Fort Myers, Fla., had just been canceled. They were deciding whether to phone the airline to rebook, or stand in a long ticket line.

Nancy MacDonald and Michael Burke also learned - after a $34 cab ride from Center City - that their flight to Boston was canceled Monday afternoon.

"We got an e-mail and a phone call from US Airways, saying the flight had been delayed until 3:15 p.m.," Nancy said. "We thought great - great that they notified us. But we never got any notification that it was canceled."

But some folks left, as scheduled, and they were all smiles.

Rob and Karen Biron, of Center City, and twin daughters Arielle and Ellie were headed to Fort Lauderdale, Fla., on a 2:15 p.m. flight that was pushed back until 4:15 p.m.

"We were stressing over the last 24 hours," Karen said. "From the drive out here on the highway, the roads were great."