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

Return flights

20 Aug - 27 Aug	Southwest Airlines
19 Aug - 26 Aug	Southwest Airlines
20 Aug - 26 Aug	Southwest Airlines
13 Aug - 19 Aug	Southwest Airlines
21 Aug - 26 Aug	Southwest Airlines
03 Aug - 08 Aug	United
05 Aug - 12 Aug	Southwest Airlines
06 Aug - 12 Aug	United
28 Aug - 04 Sep	Southwest Airlines
12 Aug - 18 Aug	Southwest Airlines
12 Aug - 17 Aug	Southwest Airlines
28 Aug - 15 Sep	Southwest Airlines
29 Aug - 01 Sep	Southwest Airlines
28 Aug - 01 Sep	Southwest Airlines

Also check the deals for one-way flights from Ontario to San Juan in August.

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 August from $461

Return flights