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

Return flights

15 Aug - 18 Aug	Frontier Airlines	direct
03 Aug - 06 Aug	Cape Air	direct
04 Aug - 06 Aug	Cape Air	direct
06 Aug - 08 Aug	Cape Air	direct
11 Aug - 21 Aug	Spirit Airlines
11 Aug - 14 Aug	Spirit Airlines
22 Aug - 25 Aug	Spirit Airlines
04 Aug - 21 Aug	Spirit Airlines
04 Aug - 14 Aug	Spirit Airlines
11 Aug - 16 Aug	Spirit Airlines

Also check the deals for one-way flights from St. Thomas 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 St. Thomas to San Juan in August from 71€

Return flights