Cheapest return flights from Seattle to Keflavik in September from $385

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

Return flights

01 Sep - 11 Sep WestJet
28 Sep - 09 Oct Icelandair direct
30 Sep - 08 Oct Icelandair direct
29 Sep - 07 Oct Icelandair direct
25 Sep - 02 Oct Icelandair direct
29 Sep - 22 Oct Icelandair direct
29 Sep - 09 Oct Icelandair direct
27 Sep - 06 Oct Icelandair direct
30 Sep - 12 Oct Icelandair direct
26 Sep - 07 Oct Icelandair direct
28 Sep - 07 Oct Icelandair direct
15 Sep - 23 Sep Icelandair direct
04 Sep - 10 Sep Icelandair direct
03 Sep - 09 Sep Icelandair direct
04 Sep - 11 Sep Icelandair direct
11 Sep - 17 Sep Icelandair direct
07 Sep - 13 Sep Icelandair direct
22 Sep - 29 Sep Icelandair direct
25 Sep - 30 Sep Icelandair direct
02 Sep - 10 Sep Icelandair direct

Also check the deals for one-way flights from Seattle 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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