More than 900 flights have been cancelled as of Wednesday afternoon, as Hurricane Idalia made landfall and disrupted travel across the US Southeast.
Southwest Airlines, which has a heavy presence in the US state of Florida, cancelled over 200 flights on Wednesday, according to data from flight-tracking service FlightAware.
Atlanta-based Delta Air Lines have cancelled 150 flights.
Airports at Tampa, Clearwater and Tallahassee in Florida have shut down operations due to the powerful hurricane.
Idalia moved into Florida's Big Bend region about 7.45am Eastern time as an "extremely dangerous" Category 3 storm, with winds approaching 125 miles per hour, the National Hurricane Center said, tying a 1896 hurricane as the strongest on record to hit that area, the Washington Post reported.
After coming ashore, Idalia turned northeastward and weakened in strength but was still expected to wreak havoc as a tropical storm in Georgia and the eastern Carolinas well into Thursday, forecasters said.
Large numbers of flights to and from the airports in Florida's Jacksonville and Sarasota, as well as Georgia's Savannah, have been cancelled.
Airlines, including Delta, United, American and Southwest have issued rebooking waivers for people travelling to and from cities in Florida, Georgia and South Carolina between Monday and Thursday.
The Federal Aviation Administration (FAA) said on Wednesday that the storm could have effects beyond the immediate area where it made landfall and urged travellers to check with airlines before heading to the airport.
Amtrak also cancelled several trains from and to Florida on Wednesday, and shortened other routes to avert areas hit by the storm.