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

Return flights

05 Dec - 13 Dec	Icelandair	direct
07 Dec - 14 Dec	Icelandair	direct
08 Dec - 15 Dec	Icelandair	direct
09 Dec - 16 Dec	Icelandair	direct
10 Dec - 17 Dec	Icelandair	direct
11 Dec - 18 Dec	Icelandair	direct
12 Dec - 19 Dec	Icelandair	direct
01 Dec - 05 Dec	Icelandair	direct
17 Dec - 22 Dec	Icelandair	direct
18 Dec - 22 Dec	Icelandair	direct
26 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 $299

Return flights