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

Return flights

04 Oct - 11 Oct	Flair Airlines
14 Oct - 21 Oct	Frontier Airlines
17 Oct - 24 Oct	Frontier Airlines
22 Oct - 29 Oct	Frontier Airlines
10 Oct - 16 Oct	Frontier Airlines
15 Oct - 23 Oct	jetBlue
28 Oct - 04 Nov	Frontier Airlines
15 Oct - 22 Oct	Hawaiian Airlines
29 Oct - 05 Nov	Hawaiian Airlines
13 Oct - 20 Oct	Frontier Airlines
07 Oct - 14 Oct	Frontier Airlines
09 Oct - 16 Oct	Flair Airlines
27 Oct - 03 Nov	Frontier Airlines
25 Oct - 01 Nov	jetBlue
30 Oct - 06 Nov	Hawaiian Airlines
31 Oct - 07 Nov	Frontier Airlines
26 Oct - 02 Nov	Frontier Airlines

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

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 Keflavik in October from $496

Return flights