$115 Cheap United flights Seattle (SEA) to Harlingen (HRL)

You can find budget-friendly return United Airlines flights from $237 from SEA to HRL by organizing your results from "Price (lowest to highest)" on Expedia. Or look for options from $115 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 United Airlines fares from Seattle - Tacoma Intl. Airport (SEA) to Valley Intl. Airport (HRL), start searching one to three months before your planned departure. Securing 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 impact the price you pay. Sunday is usually the most affordable, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your trip 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 departure from SEA to HRL with United Airlines, filter your search by "Early Morning" and "Morning." Booking an early flight generally means you're less likely to experience cancellations.**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.

Journey from SEA to HRL with United Airlines and you can look forward to a range of perks including a rewarding loyalty program. When booking through Expedia as a United Mileage Plus and One Key™ member, you may also earn OneKeyCash™* to redeem on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.