Cheapest return flights from Ontario to San Francisco in September from $239

Best time to book flights for Ontario (ONT) to San Francisco (SFO) flights at AirHint

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

Return flights

03 Sep - 14 Sep United direct
02 Sep - 13 Sep Southwest Airlines
13 Sep - 24 Sep Southwest Airlines
08 Sep - 19 Sep Southwest Airlines
03 Sep - 10 Sep Southwest Airlines
16 Sep - 18 Sep Southwest Airlines
24 Sep - 30 Sep Southwest Airlines
25 Sep - 30 Sep Southwest Airlines
26 Sep - 30 Sep Southwest Airlines
15 Sep - 23 Sep 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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