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

Return flights

04 Dec - 09 Dec	Frontier Airlines
03 Dec - 09 Dec	Southwest Airlines
10 Dec - 14 Dec	Southwest Airlines
03 Dec - 07 Dec	Southwest Airlines
12 Dec - 14 Dec	Southwest Airlines
23 Dec - 26 Dec	Volaris
31 Dec - 08 Jan	Southwest Airlines
30 Dec - 21 Jan	Avianca
07 Dec - 14 Dec	Avianca
06 Dec - 09 Dec	Avianca
09 Dec - 18 Dec	Avianca
11 Dec - 22 Dec	Avianca
13 Dec - 06 Jan	Southwest Airlines
25 Dec - 09 Jan	Volaris
14 Dec - 01 Jan	Avianca
29 Dec - 06 Jan	Southwest Airlines
13 Dec - 05 Jan	Southwest Airlines
25 Dec - 03 Jan	Volaris
27 Dec - 07 Jan	Southwest Airlines
20 Dec - 11 Jan	Avianca

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 $367

Return flights