AirHint found the following cheapest return flights from St. Louis (STL) to Lisbon (LIS) in August 2025 (see full year).

Return flights

12 Aug - 21 Aug	American Airlines
19 Aug - 26 Aug	United
17 Aug - 24 Aug	United
05 Aug - 12 Aug	United
27 Aug - 03 Sep	United
15 Aug - 22 Aug	United
21 Aug - 28 Aug	United
11 Aug - 18 Aug	United
07 Aug - 14 Aug	United
23 Aug - 30 Aug	United
25 Aug - 01 Sep	United
30 Aug - 06 Sep	United
09 Aug - 16 Aug	United

Also check the deals for one-way flights from St. Louis to Lisbon 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. Louis to Lisbon in August from $774

Return flights