Cheapest return flights from San Francisco to Keflavik in September from $521

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

Return flights

26 Sep - 07 Oct WestJet
21 Sep - 04 Oct Flair Airlines
12 Sep - 23 Sep Frontier Airlines
23 Sep - 30 Sep Flair Airlines
12 Sep - 24 Sep Frontier Airlines
16 Sep - 27 Sep Flair Airlines
17 Sep - 29 Sep Flair Airlines
27 Sep - 18 Oct Frontier Airlines
18 Sep - 22 Sep Flair Airlines
13 Sep - 23 Sep Hawaiian Airlines
13 Sep - 24 Sep jetBlue
09 Sep - 19 Sep Lufthansa
07 Sep - 19 Sep United

Also check the deals for one-way flights from San Francisco to Keflavik in September.

Skyscanner

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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