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

Return flights

24 Sep - 01 Oct	British Airways
26 Sep - 07 Oct	Delta
25 Sep - 14 Oct	Delta
24 Sep - 30 Sep	British Airways
23 Sep - 30 Sep	British Airways
30 Sep - 13 Oct	British Airways
24 Sep - 29 Sep	British Airways
26 Sep - 30 Sep	Iberia
27 Sep - 04 Oct	British Airways
26 Sep - 04 Oct	British Airways
23 Sep - 14 Oct	Air Canada
29 Sep - 13 Oct	Frontier Airlines
22 Sep - 30 Sep	Air Canada
30 Sep - 05 Oct	Air France
22 Sep - 29 Sep	Lufthansa
29 Sep - 01 Oct	Frontier Airlines
19 Sep - 29 Sep	Lufthansa
19 Sep - 30 Sep	Lufthansa
18 Sep - 30 Sep	Air Canada
19 Sep - 28 Sep	SWISS

Also check the deals for one-way flights from San Francisco to Madrid 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 Madrid in September from $445

Return flights