AirHint found the following cheapest return flights from Washington (IAD) to Keflavik (KEF) in December 2025 (see full year).

Return flights

14 Dec - 19 Dec	Icelandair	direct
08 Dec - 15 Dec	Icelandair	direct
06 Dec - 13 Dec	Icelandair	direct
11 Dec - 19 Dec	Icelandair	direct
11 Dec - 15 Dec	Icelandair	direct
24 Dec - 29 Dec	Icelandair	direct
04 Dec - 07 Dec	Icelandair	direct
27 Dec - 31 Dec	Icelandair	direct
21 Dec - 26 Dec	Icelandair	direct
18 Dec - 23 Dec	Icelandair	direct
22 Dec - 04 Jan	Scandinavian Airlines
28 Dec - 04 Jan	Lufthansa
25 Dec - 03 Jan	Scandinavian Airlines
19 Dec - 03 Jan	Icelandair	direct

Also check the deals for one-way flights from Washington to Keflavik in December.

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 Washington to Keflavik in December from $409

Return flights