Passengers at Chicago O’Hare International Airport

Airlines are waiving flight change fees and fare differences at more than 12 airports in the Mid-Atlantic and Northeastern United States ahead of a major coastal storm.

The National Weather Service issued warnings of flooding and high winds across large parts of the region from Sunday through Monday evening.

American Airlines waived fare differences and change fees for customers who booked their flights on Sunday at airports from Portland, Maine, to Newport News, Virginia, if they could travel later in the week.

Southwest Airlines, Delta Air Lines, United Airlines, JetBlue Airways, and others implemented similar flexible travel policies ahead of the storm.

Delays and cancellations were minimal on Sunday through Saturday afternoon, according to FlightAware.