Cheapest return flights from Ontario to San Francisco in September from $88

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

Return flights

07 Sep - 15 Sep Frontier Airlines direct
12 Sep - 14 Sep Frontier Airlines direct
05 Sep - 08 Sep Frontier Airlines direct
11 Sep - 14 Sep Frontier Airlines direct
12 Sep - 15 Sep Frontier Airlines direct
11 Sep - 22 Sep Frontier Airlines direct
12 Sep - 26 Sep Frontier Airlines direct
05 Sep - 07 Sep Frontier Airlines direct
24 Sep - 05 Oct Frontier Airlines
12 Sep - 24 Sep United direct
29 Sep - 30 Sep Southwest Airlines
27 Sep - 12 Oct Southwest Airlines
21 Sep - 06 Oct Southwest Airlines

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

Skyscanner

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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