$147 Cheap Frontier Airlines flights San Juan (SJU) to Islip (ISP)

Finding cheap one-way Frontier Airlines flights from SJU to ISP from $147 on Expedia is simple --- just filter by "Price (lowest to highest)." Or check out our budget-friendly return fares from $294 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.

To find affordable flights from SJU to ISP with Frontier Airlines, begin your search about one month before your intended departure. You can save 17% when you lock in your international tickets 18 to 29 days ahead instead of booking four to five months in advance. Another tip? Booking on Sunday can lead to average savings of 17% compared to Friday (the most expensive day).**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.

Find Frontier Airlines's earliest flights from SJU to ISP by using our "Morning" and "Early Morning" filters. Not only will you get to your destination sooner, early departures also have a 20% less chance of being 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.

Travel from SJU to ISP with Frontier Airlines and you'll enjoy a range of perks starting with a rewarding loyalty program. When booking through Expedia as a Frontier Miles and One Key™ member, you may also earn OneKeyCash™* to use on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.