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

Return flights

21 Sep - 02 Oct	British Airways
17 Sep - 24 Sep	American Airlines
17 Sep - 25 Sep	Iberia
29 Sep - 31 Oct	British Airways
21 Sep - 30 Sep	British Airways
23 Sep - 30 Sep	Iberia
24 Sep - 29 Oct	Iberia
23 Sep - 21 Oct	Iberia
22 Sep - 13 Oct	British Airways
16 Sep - 23 Sep	British Airways
29 Sep - 25 Oct	British Airways
30 Sep - 25 Oct	British Airways
30 Sep - 09 Oct	British Airways
16 Sep - 25 Sep	British Airways
24 Sep - 18 Oct	Iberia
23 Sep - 18 Oct	Iberia
18 Sep - 24 Sep	British Airways
09 Sep - 23 Sep	SWISS
13 Sep - 21 Sep	Hawaiian Airlines
26 Sep - 30 Sep	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 $526

Return flights