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

Return flights

11 Aug - 15 Aug	United
25 Aug - 28 Aug	Southwest Airlines
11 Aug - 14 Aug	United
10 Aug - 15 Aug	United
18 Aug - 21 Aug	Spirit Airlines
12 Aug - 16 Aug	United
18 Aug - 29 Aug	Spirit Airlines
10 Aug - 14 Aug	United
11 Aug - 29 Aug	Spirit Airlines
24 Aug - 11 Sep	Spirit Airlines
10 Aug - 21 Aug	Spirit Airlines
29 Aug - 03 Sep	Southwest Airlines
29 Aug - 02 Sep	Southwest Airlines
27 Aug - 02 Sep	United

Also check the deals for one-way flights from Austin 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 Austin to San Juan in August from 194€

Return flights