AirHint found the following cheapest return flights from Ontario (ONT) to San Jose (SJO) in October 2025 (see full year).

Return flights

18 Oct - 23 Oct	Avianca
14 Oct - 21 Oct	Avianca
11 Oct - 16 Oct	Avianca
11 Oct - 14 Oct	Avianca
18 Oct - 21 Oct	Avianca
02 Oct - 04 Nov	Avianca
11 Oct - 18 Oct	Avianca
20 Oct - 28 Oct	Southwest Airlines
13 Oct - 17 Oct	jetBlue
29 Oct - 13 Nov	Southwest Airlines
18 Oct - 22 Oct	Avianca
03 Oct - 05 Nov	Southwest Airlines
21 Oct - 27 Oct	Southwest Airlines
31 Oct - 22 Nov	Southwest Airlines
29 Oct - 11 Nov	Southwest Airlines

Also check the deals for one-way flights from Ontario to San Jose in October.

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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Cheapest return flights from Ontario to San Jose in October from $309

Return flights