$109 Cheap American Airlines flights Seattle (SEA) to Harlingen (HRL)

Grab affordable round-trip American Airlines flights from $217 from SEA to HRL by filtering your results from "Price (lowest to highest)" on Expedia. Or look for bargains from $109 for a one-way trip.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

To find cheap American Airlines fares from Seattle - Tacoma Intl. Airport (SEA) to Valley Intl. Airport (HRL), start searching one to three months before your planned departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also affect how much you pay. Sunday is usually the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your flight on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

To find the earliest departures from SEA to HRL with American Airlines, filter your search by "Early Morning" and "Morning." Choosing an early flight usually means cancellations are less likely.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.