Cheapest one-way flights from Ontario to San Juan in December from $157

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

One-Way flights

31 Dec Frontier Airlines
02 Dec Southwest Airlines
03 Dec Southwest Airlines
29 Dec Frontier Airlines
25 Dec Frontier Airlines
06 Dec Southwest Airlines
23 Dec Frontier Airlines
28 Dec Frontier Airlines
20 Dec Frontier Airlines
30 Dec Frontier Airlines

Also check the deals for return flights from Ontario to San Juan in December.

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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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