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

Return flights

09 Sep - 30 Sep	SWISS
23 Sep - 30 Sep	LEVEL
28 Sep - 07 Oct	LEVEL
27 Sep - 30 Sep	LEVEL
23 Sep - 07 Oct	LEVEL
13 Sep - 26 Sep	LEVEL
13 Sep - 20 Sep	LEVEL
09 Sep - 23 Sep	LEVEL
13 Sep - 21 Sep	LEVEL
30 Sep - 13 Oct	Air Canada
16 Sep - 23 Sep	Air Canada
02 Sep - 10 Sep	Air Canada
20 Sep - 23 Sep	LEVEL
23 Sep - 07 Oct	TAP	direct
24 Sep - 01 Oct	Brussels Airlines
20 Sep - 18 Oct	LEVEL
29 Sep - 14 Oct	TAP	direct
24 Sep - 01 Oct	TAP	direct
10 Sep - 01 Oct	Hawaiian Airlines
29 Sep - 13 Oct	SWISS

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.

Book a cheap hotel in Lisbon

Cheap car rent in Lisbon

Cheapest return flights from San Francisco to Lisbon in September from $389

Return flights