Cheapest return flights from Islip to San Juan in January from $180

AirHint found the following cheapest return flights from Islip (ISP) to San Juan (SJU) in January 2026 (see full year).

Return flights

10 Jan - 13 Jan Frontier Airlines
15 Jan - 22 Jan Frontier Airlines
08 Jan - 12 Jan Frontier Airlines
26 Jan - 04 Feb Frontier Airlines
23 Jan - 31 Jan Frontier Airlines
25 Jan - 28 Jan Frontier Airlines
10 Jan - 17 Jan Frontier Airlines
19 Jan - 28 Jan Frontier Airlines
15 Jan - 24 Jan Frontier Airlines
04 Jan - 12 Jan Frontier Airlines
10 Jan - 18 Jan Frontier Airlines
20 Jan - 13 Feb Frontier Airlines
29 Jan - 02 Feb Frontier Airlines

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

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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.

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