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

Return flights

23 Sep - 30 Sep	Hawaiian Airlines
23 Sep - 01 Oct	Alaska Airlines
16 Sep - 24 Sep	Alaska Airlines
10 Sep - 18 Sep	Alaska Airlines
08 Sep - 16 Sep	Alaska Airlines
15 Sep - 23 Sep	Alaska Airlines
17 Sep - 25 Sep	Alaska Airlines
09 Sep - 17 Sep	Alaska Airlines
29 Sep - 07 Oct	Alaska Airlines
30 Sep - 08 Oct	Alaska Airlines
18 Sep - 26 Sep	Alaska Airlines
22 Sep - 30 Sep	Alaska Airlines
28 Sep - 06 Oct	Alaska Airlines
25 Sep - 03 Oct	Alaska Airlines
01 Sep - 09 Sep	Alaska Airlines
27 Sep - 05 Oct	Alaska Airlines
24 Sep - 02 Oct	Alaska Airlines

Also check the deals for one-way flights from San Jose to Keflavik 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 Jose to Keflavik in September from 553€

Return flights