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

Return flights

09 Sep - 16 Sep	TAP
16 Sep - 23 Sep	TAP
08 Sep - 15 Sep	SWISS
01 Sep - 09 Sep	SWISS
07 Sep - 11 Sep	Alaska Airlines
11 Sep - 22 Sep	Hawaiian Airlines
11 Sep - 18 Sep	SWISS
12 Sep - 19 Sep	Hawaiian Airlines
12 Sep - 01 Oct	Alaska Airlines
10 Sep - 17 Sep	Hawaiian Airlines
09 Sep - 29 Sep	Hawaiian Airlines
30 Sep - 07 Oct	Iberia For Level
25 Sep - 07 Oct	SWISS
03 Sep - 01 Oct	British Airways
26 Sep - 12 Oct	Frontier Airlines
24 Sep - 24 Oct	Hawaiian Airlines
29 Sep - 07 Oct	Hawaiian Airlines
25 Sep - 12 Oct	Alaska Airlines
26 Sep - 14 Oct	Sun Country Airlines
24 Sep - 25 Oct	Alaska 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 358€

Return flights