Cheapest return flights from Ontario to San Francisco in May from $73

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 May 2025 (see full year).

Return flights

10 May - 12 May Frontier Airlines direct
04 May - 15 May Frontier Airlines direct
01 May - 08 May Frontier Airlines direct
15 May - 26 May Frontier Airlines direct
01 May - 14 Jun Frontier Airlines direct
26 May - 02 Jun Frontier Airlines direct
21 May - 26 May Frontier Airlines
14 May - 20 May United direct
20 May - 21 May Frontier Airlines
03 May - 24 May Southwest Airlines
01 May - 04 May Southwest Airlines
31 May - 31 May Southwest Airlines
21 May - 04 Jun Southwest Airlines
31 May - 07 Jun Southwest Airlines

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

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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