AirHint found the following cheapest return flights from St. Louis (STL) to San Juan (SJU) in October 2025 (see full year).

Return flights

25 Oct - 28 Oct	American Airlines
12 Oct - 23 Oct	American Airlines
03 Oct - 07 Oct	Southwest Airlines
19 Oct - 22 Oct	American Airlines
19 Oct - 23 Oct	American Airlines
27 Oct - 02 Nov	United
31 Oct - 03 Nov	Frontier Airlines
04 Oct - 08 Oct	United
31 Oct - 04 Nov	Delta

Also check the deals for one-way flights from St. Louis to San Juan in October.

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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Cheapest return flights from St. Louis to San Juan in October from $225

Return flights