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

Return flights

13 Aug - 20 Aug	Frontier Airlines
18 Aug - 22 Aug	Southwest Airlines
04 Aug - 08 Aug	Frontier Airlines
28 Aug - 02 Sep	Frontier Airlines
20 Aug - 26 Aug	Southwest Airlines
19 Aug - 21 Aug	Southwest Airlines
13 Aug - 19 Aug	Southwest Airlines
19 Aug - 23 Aug	Avianca
18 Aug - 25 Aug	Southwest Airlines
13 Aug - 18 Aug	Southwest Airlines
12 Aug - 19 Aug	Southwest Airlines
30 Aug - 27 Sep	Southwest Airlines
28 Aug - 01 Sep	Southwest Airlines

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

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 August from 325€

Return flights