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

Return flights

01 Dec - 18 Dec	Southwest Airlines
14 Dec - 29 Dec	Southwest Airlines
20 Dec - 22 Dec	Southwest Airlines
29 Dec - 05 Jan	Southwest Airlines
23 Dec - 06 Jan	Southwest Airlines
24 Dec - 31 Dec	Southwest Airlines
21 Dec - 27 Dec	Southwest Airlines
25 Dec - 05 Jan	Southwest Airlines
25 Dec - 03 Jan	Southwest Airlines
28 Dec - 02 Jan	Southwest Airlines
19 Dec - 02 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.

Book a cheap hotel in San Jose

Cheap car rent in San Jose

Cheapest return flights from Ontario to San Jose in December from 529€

Return flights