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

Return flights

09 Sep - 23 Sep	TAP
30 Sep - 10 Oct	American Airlines
23 Sep - 01 Oct	American Airlines
23 Sep - 30 Sep	SWISS
09 Sep - 16 Sep	TAP
21 Sep - 06 Oct	SWISS
07 Sep - 15 Sep	SWISS
09 Sep - 22 Sep	SWISS
08 Sep - 23 Sep	SWISS
09 Sep - 17 Sep	SWISS
07 Sep - 07 Oct	SWISS
21 Sep - 30 Sep	Iberia For Level
22 Sep - 30 Sep	SWISS
23 Sep - 29 Sep	Iberia For Level
26 Sep - 03 Oct	Alaska Airlines
20 Sep - 06 Oct	Iberia For Level
17 Sep - 10 Oct	Alaska Airlines
27 Sep - 04 Oct	Iberia For Level
17 Sep - 18 Oct	TAP
17 Sep - 02 Oct	Turkish Airlines

Also check the deals for one-way flights from San Francisco to London 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 London in September from $420

Return flights