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

Return flights

25 Aug - 03 Sep	jetBlue
17 Aug - 02 Sep	Air Canada
19 Aug - 28 Aug	United
11 Aug - 22 Aug	United
21 Aug - 28 Aug	United
30 Aug - 02 Sep	Scandinavian Airlines
19 Aug - 26 Aug	United
16 Aug - 23 Aug	Scandinavian Airlines
26 Aug - 20 Sep	United
31 Aug - 08 Sep	United
29 Aug - 05 Sep	United
13 Aug - 20 Aug	Air Canada
11 Aug - 20 Aug	United
18 Aug - 25 Aug	United
13 Aug - 23 Aug	United
11 Aug - 15 Aug	jetBlue
23 Aug - 02 Sep	British Airways

Also check the deals for one-way flights from Washington 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 Washington to Lisbon in August from 590€

Return flights