Cheapest return flights from Islip to San Juan in December from $284

AirHint found the following cheapest return flights from Islip (ISP) to San Juan (SJU) in December 2025 (see full year).

Return flights

12 Dec - 15 Dec Frontier Airlines
09 Dec - 17 Dec Frontier Airlines
10 Dec - 14 Dec Frontier Airlines
05 Dec - 10 Dec Frontier Airlines
03 Dec - 09 Dec Frontier Airlines
11 Dec - 14 Dec Frontier Airlines
05 Dec - 09 Dec Frontier Airlines
04 Dec - 09 Dec Frontier Airlines
10 Dec - 15 Dec Frontier Airlines
06 Dec - 08 Dec Frontier Airlines
23 Dec - 08 Jan Frontier Airlines
24 Dec - 02 Jan Frontier Airlines
25 Dec - 02 Jan Frontier Airlines
23 Dec - 02 Jan Frontier Airlines
26 Dec - 02 Jan Frontier Airlines
23 Dec - 03 Jan Frontier Airlines
30 Dec - 05 Jan Frontier Airlines
19 Dec - 03 Jan Frontier Airlines

Also check the deals for one-way flights from Islip to San Juan in December.

Skyscanner

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

Book a cheap hotel in San Juan

Cheap car rent in San Juan

Feel free to contact us with any feedback or request another flight research.