Cheapest return flights from Chicago to San Juan in September from $270

AirHint found the following cheapest return flights from Chicago (MDW) to San Juan (SJU) in September 2025 (see full year).

Return flights

07 Sep - 12 Sep Frontier Airlines
08 Sep - 11 Sep Frontier Airlines
13 Sep - 20 Sep Frontier Airlines
21 Sep - 25 Sep Frontier Airlines
07 Sep - 11 Sep Frontier Airlines
19 Sep - 21 Sep Frontier Airlines
29 Sep - 06 Oct Frontier Airlines
29 Sep - 03 Oct Frontier Airlines
20 Sep - 26 Sep Frontier Airlines
18 Sep - 25 Sep Frontier Airlines
08 Sep - 12 Sep Frontier Airlines
18 Sep - 21 Sep Frontier Airlines
26 Sep - 11 Oct Frontier Airlines
26 Sep - 17 Oct Frontier Airlines
26 Sep - 04 Oct Frontier Airlines
26 Sep - 03 Oct Frontier Airlines

Also check the deals for one-way flights from Chicago to San Juan in September.

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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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