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

Return flights

30 Sep - 06 Oct	Air Canada
30 Sep - 08 Oct	Air Canada
23 Sep - 30 Sep	Lufthansa
28 Sep - 15 Oct	SWISS
28 Sep - 14 Oct	SWISS
22 Sep - 29 Sep	Air Canada
22 Sep - 07 Oct	SWISS
22 Sep - 30 Sep	Lufthansa
22 Sep - 08 Oct	SWISS
29 Sep - 06 Oct	Frontier Airlines
22 Sep - 26 Sep	Frontier Airlines
23 Sep - 29 Sep	SWISS
30 Sep - 10 Oct	American Airlines
22 Sep - 02 Oct	Frontier Airlines
23 Sep - 26 Sep	Alaska Airlines
25 Sep - 01 Oct	American Airlines
24 Sep - 27 Sep	Alaska Airlines
23 Sep - 27 Sep	Alaska Airlines
18 Sep - 26 Sep	Frontier Airlines
24 Sep - 30 Sep	SWISS

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 $485

Return flights