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

Return flights

30 Sep - 06 Oct	SWISS
23 Sep - 30 Sep	British Airways
21 Sep - 30 Sep	British Airways
29 Sep - 31 Oct	SWISS
16 Sep - 23 Sep	SWISS
21 Sep - 02 Oct	Lufthansa
30 Sep - 25 Oct	British Airways
17 Sep - 24 Sep	Delta
22 Sep - 30 Sep	British Airways
30 Sep - 09 Oct	Delta
17 Sep - 03 Oct	Delta
22 Sep - 29 Sep	British Airways
26 Sep - 06 Oct	Brussels Airlines
15 Sep - 24 Sep	Lufthansa
22 Sep - 25 Sep	Frontier Airlines
16 Sep - 25 Sep	SWISS
27 Sep - 04 Oct	British Airways
19 Sep - 24 Sep	Frontier Airlines
20 Sep - 18 Oct	Frontier Airlines
25 Sep - 18 Oct	British Airways

Also check the deals for one-way flights from San Francisco to Lisbon in September.

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 September from 519€

Return flights