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

Return flights

14 Aug - 21 Aug	Frontier Airlines
17 Aug - 23 Aug	United
19 Aug - 23 Aug	United
12 Aug - 19 Aug	American Airlines
13 Aug - 19 Aug	American Airlines
10 Aug - 16 Aug	United
21 Aug - 27 Aug	Frontier Airlines
20 Aug - 26 Aug	Southwest Airlines
05 Aug - 11 Aug	Frontier Airlines
01 Aug - 03 Aug	Frontier Airlines
27 Aug - 07 Sep	Delta

Also check the deals for one-way flights from San Francisco 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 San Francisco to San Juan in August from $387

Return flights