$119 Cheap United flights Harlingen (HRL) to Seattle (SEA)

You can discover cheap round-trip United Airlines flights from $228 from HRL to SEA by sorting your results from "Price (lowest to highest)" on Expedia. Or look for deals from $119 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 Valley Intl. Airport (HRL) to Seattle - Tacoma Intl. Airport (SEA), start searching one to three months before your intended 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 influence the price you pay. Sunday is typically the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by choosing to book 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.

Browse United Airlines's earliest flights from HRL to SEA by selecting the "Early Morning" and "Morning" filters. Not only will you get to where you're going sooner, early departures are also 20% less likely to be canceled.**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.

Depart from HRL to SEA with United Airlines and you'll enjoy a range of benefits starting with a rewarding loyalty program. When you book 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.