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

Return flights

22 Sep - 08 Oct	SWISS
30 Sep - 03 Oct	Hawaiian Airlines
26 Sep - 22 Oct	Frontier Airlines
24 Sep - 16 Oct	TAP
15 Sep - 26 Sep	TAP
09 Sep - 04 Oct	FrenchBee
26 Sep - 07 Oct	Frontier Airlines
14 Sep - 04 Oct	WestJet
25 Sep - 09 Oct	Frontier Airlines
25 Sep - 28 Sep	Frontier Airlines
28 Sep - 18 Oct	Iberia
19 Sep - 28 Sep	Frontier Airlines
16 Sep - 23 Sep	TAP
21 Sep - 29 Sep	Frontier Airlines
27 Sep - 18 Oct	Frontier Airlines
13 Sep - 20 Sep	FrenchBee
26 Sep - 30 Sep	Frontier Airlines
16 Sep - 30 Sep	Air Canada
20 Sep - 27 Sep	Frontier Airlines
12 Sep - 20 Sep	Frontier Airlines

Also check the deals for one-way flights from San Francisco to Istanbul 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 Istanbul in September from $717

Return flights