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

Return flights

03 Dec - 09 Dec	Southwest Airlines
12 Dec - 19 Dec	Southwest Airlines
05 Dec - 08 Dec	Southwest Airlines
15 Dec - 21 Dec	Southwest Airlines
09 Dec - 15 Dec	Southwest Airlines
07 Dec - 18 Jan	Southwest Airlines
31 Dec - 08 Jan	Southwest Airlines
01 Dec - 08 Dec	Southwest Airlines
13 Dec - 04 Jan	Avianca
25 Dec - 04 Jan	Avianca
25 Dec - 03 Jan	Avianca
19 Dec - 24 Dec	Southwest Airlines
14 Dec - 03 Jan	Southwest Airlines
19 Dec - 06 Jan	Southwest Airlines
19 Dec - 07 Jan	Southwest Airlines
26 Dec - 27 Dec	Southwest Airlines
19 Dec - 04 Jan	Southwest Airlines
28 Dec - 04 Jan	Southwest Airlines

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

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 December from $538

Return flights