AirHint found the following cheapest return flights from Seattle (SEA) to Keflavik (KEF) in January 2026 (see full year).

Return flights

08 Jan - 15 Jan	Lufthansa
10 Jan - 17 Jan	Lufthansa
15 Jan - 22 Jan	Lufthansa
17 Jan - 24 Jan	Lufthansa
22 Jan - 29 Jan	Lufthansa
29 Jan - 05 Feb	Lufthansa
09 Jan - 16 Jan	Lufthansa
16 Jan - 23 Jan	Lufthansa
23 Jan - 30 Jan	Lufthansa
30 Jan - 06 Feb	Lufthansa
01 Jan - 08 Jan	Lufthansa
24 Jan - 31 Jan	Lufthansa
31 Jan - 07 Feb	Lufthansa
27 Jan - 11 Feb	Icelandair	direct
26 Jan - 02 Feb	Icelandair	direct
27 Jan - 03 Feb	Icelandair	direct
29 Jan - 05 Feb	Icelandair	direct
28 Jan - 04 Feb	Icelandair	direct
25 Jan - 01 Feb	Icelandair	direct
30 Jan - 06 Feb	Icelandair	direct

Also check the deals for one-way flights from Seattle to Keflavik in January.

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 Seattle to Keflavik in January from $525

Return flights