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

Return flights

02 Oct - 06 Oct	Frontier Airlines
17 Oct - 21 Oct	Frontier Airlines
21 Oct - 25 Oct	Frontier Airlines
05 Oct - 08 Oct	Frontier Airlines
31 Oct - 04 Nov	United
27 Oct - 09 Nov	Frontier Airlines
08 Oct - 13 Oct	Frontier Airlines
01 Oct - 04 Oct	Frontier Airlines
01 Oct - 08 Oct	Frontier Airlines
08 Oct - 14 Oct	Alaska Airlines
06 Oct - 14 Oct	Frontier Airlines
07 Oct - 14 Oct	Frontier Airlines

Also check the deals for one-way flights from San Francisco 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 San Francisco to San Juan in October from 314€

Return flights