$114 Cheap United flights San Diego (SAN) to Harlingen (HRL)

Landing cheap one-way United Airlines flights from SAN to HRL from $114 on Expedia couldn't be easier --- just filter by "Price (lowest to highest)." Alternatively, check out our affordable return fares from $232 for your next exciting adventure.**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.

Look for affordable United Airlines flights from San Diego Intl. Airport (SAN) to Valley Intl. Airport (HRL) one to three months prior to your departure day. Travelers who book domestic flights 34 to 86 days in advance can save 25% compared to those who book just 6 to 12 days ahead. Regardless of fare type and journey, the best day of the week to book a domestic flight is usually Sunday and the most expensive is typically Monday. Passengers who book on a Sunday can save 6% on average compared to those who book their travel on a Monday.**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.

Filter your results by "Morning" and "Early Morning" to find the earliest departures from SAN to HRL. Jetting off early means you're 20% 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.

A rewarding loyalty program and the chance to rack up points through United Mileage Plus are the start of the reasons to jet off from SAN to HRL with United Airlines. Plus, by joining Expedia's free One Key™ program, you can receive OneKeyCash™* alongside any airline loyalty program earnings. It's yours to spend on future travel plans.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.