AirHint found the following cheapest return flights from San Francisco (SFO) to San Jose (SJO) in September 2025 (see full year).

Return flights

23 Sep - 30 Sep	Frontier Airlines
22 Sep - 26 Sep	jetBlue
09 Sep - 16 Sep	jetBlue
24 Sep - 30 Sep	Frontier Airlines
08 Sep - 15 Sep	Frontier Airlines
08 Sep - 14 Sep	Frontier Airlines
19 Sep - 22 Sep	Hawaiian Airlines
12 Sep - 14 Sep	Frontier Airlines
24 Sep - 28 Sep	Frontier Airlines
23 Sep - 29 Sep	Copa

Also check the deals for one-way flights from San Francisco to San Jose in September.

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 Jose in September from $304

Return flights