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

Return flights

12 Aug - 26 Aug	United
20 Aug - 27 Aug	United
20 Aug - 28 Aug	United
20 Aug - 10 Sep	United
18 Aug - 03 Sep	United
18 Aug - 03 Sep	TAP	direct
11 Aug - 21 Aug	Delta
24 Aug - 09 Sep	British Airways
19 Aug - 25 Aug	SWISS
20 Aug - 30 Aug	SWISS
21 Aug - 28 Aug	United
09 Aug - 23 Aug	SWISS
09 Aug - 22 Aug	Delta
07 Aug - 20 Aug	SWISS
18 Aug - 01 Sep	Brussels Airlines
27 Aug - 03 Sep	Delta
30 Aug - 24 Sep	Frontier Airlines
27 Aug - 01 Sep	Air France
20 Aug - 10 Sep	TAP	direct
28 Aug - 02 Sep	Frontier Airlines

Also check the deals for one-way flights from San Francisco 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 San Francisco to Lisbon in August from 548€

Return flights