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

Return flights

07 Dec - 14 Dec	Icelandair
07 Dec - 13 Dec	Icelandair
10 Dec - 14 Dec	Southwest Airlines
09 Dec - 16 Dec	jetBlue
31 Dec - 07 Jan	Air Canada
14 Dec - 18 Dec	jetBlue
06 Dec - 12 Dec	Icelandair
05 Dec - 11 Dec	jetBlue
08 Dec - 10 Dec	Scandinavian Airlines
08 Dec - 11 Dec	Scandinavian Airlines
24 Dec - 27 Dec	Southwest Airlines
29 Dec - 06 Jan	jetBlue
29 Dec - 05 Jan	jetBlue
28 Dec - 05 Jan	jetBlue
28 Dec - 04 Jan	Air Canada
31 Dec - 04 Jan	jetBlue
27 Dec - 04 Jan	jetBlue
24 Dec - 01 Jan	Southwest Airlines
25 Dec - 01 Jan	Air Canada
26 Dec - 02 Jan	WestJet

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 671€

Return flights