Airlines are allowing passengers to change their travel plans as Hurricane Florence spins closer to the U.S. East Coast.

Hurricane Florence, currently a Category 4 storm with maximum sustained winds of 130 miles per hour, could hit the southeastern U.S. or mid-Atlantic region by the end of the week, according to the National Oceanic and Atmospheric Administration. Constant high winds of at least 36 knots, about 41 miles per hour, can prevent Federal Aviation Administration staff from servicing radars and radio towers, so some systems could be shut down preemptively, the agency said.

American Airlines said travelers whose plans could be affected by the storm can change their travel dates without paying change fees, which can cost $200 plus a difference in fare, if they can travel between Sept. 10 and Sept. 19.

The waivers for Hurricane Florence cover 23 airports, including Charlotte Douglas Airport, American's second-largest hub, where it has about 670 flights a day. So far, American Airlines flights have not been canceled due to the storm, the carrier said.