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

Return flights

01 Dec - 09 Dec	Southwest Airlines
04 Dec - 09 Dec	Southwest Airlines
04 Dec - 14 Dec	Southwest Airlines
06 Dec - 16 Dec	Southwest Airlines
04 Dec - 08 Dec	Southwest Airlines
07 Dec - 21 Dec	Southwest Airlines
12 Dec - 21 Dec	Southwest Airlines
14 Dec - 21 Dec	Southwest Airlines
28 Dec - 11 Jan	Southwest Airlines
16 Dec - 30 Dec	Southwest Airlines
21 Dec - 26 Dec	Southwest Airlines
25 Dec - 01 Jan	Southwest Airlines
23 Dec - 06 Jan	Southwest Airlines

Also check the deals for one-way flights from Ontario to San Juan 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 Juan in December from 347€

Return flights