Airlines cancelled more than 3,000 flights for Thursday and Friday as Hurricane Matthew moved closer to the Florida coast, bringing high winds and heavy rain.
The Fort Lauderdale airport shut down on Thursday morning, and further north the Orlando airport expected to do the same by nighttime.
American Airlines said that by late afternoon it had cancelled all flights for the evening at several airports in Florida including Miami, where it has a large hub operation.
By 6 p.m. Eastern time, flight-tracking service FlightAware.com reported that more than 1,500 Thursday flights within the U.S. had been scrapped, with the largest numbers at Fort Lauderdale and Miami. American was the hardest-hit carrier, followed by Southwest Airlines and JetBlue Airways.
FlightAware said airlines had already cancelled another 1,600 flights scheduled for Friday. Delta Air Lines said cancellations were likely to spread to coastal Georgia and South Carolina on Saturday.
Airlines often cancel flights before storms hit to prevent passengers from being stranded at airports and to keep their planes in position to recover after the bad weather passes.
Many airlines were letting passengers alter their plans and delay travel for a few days without incurring the usual fee for changing a ticket, which can be $200 for domestic flights. Some, including United Airlines, JetBlue and Spirit Airlines, also said they would waive the fare difference for the new ticket.
At Fort Lauderdale-Hollywood International Airport on Thursday, the last flight out was a Southwest jet to Baltimore, which just beat the 10:30 a.m. curtain. Airport officials said Southwest would try to resume normal operations Saturday.
Orlando International Airport officials tweeted that they expected the airport to close to commercial traffic by 8 p.m. and not reopen until Saturday. As the storm closed in, workers tied down jet bridges, lowered cranes in a construction area, and put away vehicles and other equipment.
American hoped to resume flying around midday Friday in Miami, Fort Lauderdale and Palm Beach but cancelled all Friday flights in Orlando and Jacksonville. It cancelled service Friday and Saturday in Savannah, Georgia, and Saturday flights at Charleston and Myrtle Beach, South Carolina, and Wilmington, North Carolina.
While airport closings and flight cancellations made it hard to reach Florida, coastal residents from Florida to South Carolina headed north and inland to escape the hurricane. Hotels in Charlotte, North Carolina, reported brisk business.
Amtrak suspended passenger rail service through Friday between Miami and New York and the auto train between Lorton, Virginia, and Sanford, Florida. A line that normally runs from New York to Savannah, Georgia, only went as far south as Washington.
Earlier in the week, several airports in the Caribbean closed, forcing airlines to cancel flights there.
Cruise lines rerouted ships this week to avoid the storm, which in some cases will mean more days at sea or skipping some Caribbean ports.