AirHint found the following cheapest return flights from Ontario (ONT) to San Francisco (SFO)
in May 2025 (see full year ).
Return flights
02 May
- 05 May
Frontier Airlines
$ 56
direct
08 May
- 12 May
Frontier Airlines
$ 56
direct
11 May
- 12 May
Frontier Airlines
$ 56
direct
01 May
- 05 May
Frontier Airlines
$ 56
direct
15 May
- 26 May
Frontier Airlines
$ 57
direct
01 May
- 04 May
Frontier Airlines
$ 57
direct
02 May
- 04 May
Frontier Airlines
$ 57
direct
08 May
- 11 May
Frontier Airlines
$ 57
direct
15 May
- 19 May
Frontier Airlines
$ 60
direct
12 May
- 22 May
Frontier Airlines
$ 60
direct
29 May
- 01 Jun
Frontier Airlines
$ 69
direct
26 May
- 06 Jun
Frontier Airlines
$ 148
direct
31 May
- 02 Jun
Southwest Airlines
$ 248
26 May
- 01 Jun
Southwest Airlines
$ 358
Also check the deals for one-way flights from Ontario to San Francisco in May .
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.