“Hurricane and tropical storm conditions are expected over northeastern portions of the Yucatan Peninsula of Mexico today where Tropical Storm and Hurricane Warnings are in effect,” the National Hurricane Center said Wednesday morning.

Travelers heading to or coming back from Mexico may find their travel plans impacted. While U.S. flights aren’t really seeing an impact yet Wednesday, 12% of flights to Cancun, Mexico, have been canceled, and another 14% have been delayed, according to online flight tracker FlightAware. Among flights originating from the airport, 16% were canceled, while 19% were delayed.

Airlines have also begun issuing waivers, and cruise lines have changed their itineraries.

Which airlines have issued Mexico travel waivers?

• Alaska Airlines: Travelers with flights scheduled to and from Cancun, Mexico (CUN) between Sept. 25 and Sept. 27 may rebook or cancel their flights for free. Travelers must change or cancel their flight prior to its departure. Their new travel date must be no later than Sept. 30. Customers who cancel their flight will get a credit for use on future travel.
• American Airlines: Travelers with American Airlines flights scheduled to, through, and from Cancun (CUN) and Cozumel (CZM) through Sept. 27 may rebook their flights for free. Travel must be rebooked by Sept. 27 and completed by Oct. 4 within the same fare class and cities as first booked to be eligible for waived fees.
• Delta Air Lines: Travelers with Delta flights scheduled to, through and from Cancun (CUN) between Sept. 25 and Sept. 27 may rebook their flights for free. Tickets must be reissued by the end of the day on Oct. 4, completed no later than Oct. 4, and within the same fare class to avoid differences in fare. Travelers who cannot fly by Oct. 4 may be subject to fare differences, but change fees will be waived. Customers who choose to cancel their flights will be issued flight credit valid for one year from the date the ticket was first issued.
• Frontier Airlines: Travelers with Frontier flights scheduled to, through and from Cancun (CUN) through Sept. 25 may rebook without change fees, but fare differences may apply. Travelers who choose to cancel their flights are eligible for travel credit, less any applicable cancellation or carrier fees, according to the airline.
• Southwest Airlines: Travelers with Southwest flights scheduled to, through and from Cancun (CUN) through Sept. 25 may rebook travel or fly standby for free within 14 days of their original travel dates. Travel must be between the same cities as originally scheduled to avoid extra charges. Customers who opt not to travel can request a refund for the unused portion of their ticket or save the credit for a future flight.
• Spirit Airlines: Travelers with Spirit flights scheduled to, through and from Cancun (CUN) through Sept. 25 may rebook without penalty if they fly by Oct. 2. Fare differences will apply for travel after Oct. 2.
• United Airlines: Travelers with United flights scheduled to, through and from Cancun (CUN), Cozumel (CZM) and Tulum (TQO) before Sept. 27 may rebook their flights for free. United will waive change fees and fare differences for travel completed by Oct. 4 within the same fare class and between the same cities as originally booked.