Cheapest return flights from Ontario to San Francisco in September from 85€

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

Return flights

19 Sep - 21 Sep Frontier Airlines direct
25 Sep - 30 Sep Frontier Airlines
25 Sep - 30 Sep United direct
23 Sep - 24 Sep Frontier Airlines
26 Sep - 29 Sep Southwest Airlines
26 Sep - 30 Sep Southwest Airlines
26 Sep - 27 Sep Southwest Airlines
15 Sep - 22 Sep Southwest Airlines
26 Sep - 03 Oct Southwest Airlines
29 Sep - 30 Sep Southwest Airlines
15 Sep - 30 Sep Southwest Airlines
30 Sep - 01 Oct Southwest Airlines
25 Sep - 03 Oct Southwest Airlines
19 Sep - 03 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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