As Southern California braces for its first tropical storm in more than 80 years, airlines flying to and from the area—including Delta and Southwest Airlines—have advised customers of potential delays or cancellations in the coming days.

Southwest has advised that “based on the forecasted weather conditions” for Sunday and Monday, as a result of Hurricane Hilary, its scheduled services may be disrupted at different Southern California airports, including Long Beach, Los Angeles and Orange County.

Therefore, Southwest will be allowing anyone with flights booked to, from or through the cities listed in its travel advisory to change their reservation within 14 days of their original travel date without paying additional charges. To change a booking for free, customers are eligible to reschedule their travel plans online or from their mobile device, according to the airline.

Delta, meanwhile, is waiving rebooking fees for customers traveling to, from or through LGB and LAX, among several others, so long as the rebooked travel occurs on or before Aug. 24.

“If travel is not able to be rescheduled within these guidelines, customers may cancel their reservation and apply any unused value of the ticket toward the purchase of a new ticket for a period of one year from the original ticket issuance,” according to Delta Airlines.

A spokesperson with Long Beach Airport did not immediately respond to a request for information on cancellations and delays. According to FlightAware, Southwest has canceled 47 flights that were scheduled at Long Beach Airport on Sunday and another 19 that were scheduled on Monday.

Hurricane Hilary: When it will hit Long Beach and how to prepare