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

Return flights

01 Dec - 11 Jan	Scandinavian Airlines
02 Dec - 12 Dec	TAP	direct
07 Dec - 14 Dec	TAP	direct
09 Dec - 16 Dec	TAP	direct
05 Dec - 08 Dec	Icelandair
05 Dec - 12 Dec	Icelandair
03 Dec - 10 Dec	TAP	direct
05 Dec - 12 Dec	TAP	direct
16 Dec - 23 Dec	SWISS
25 Dec - 18 Jan	Scandinavian Airlines
30 Dec - 06 Jan	TAP	direct
25 Dec - 17 Jan	Scandinavian Airlines
13 Dec - 20 Dec	Turkish Airlines
15 Dec - 10 Jan	Icelandair
01 Dec - 11 Jan	TAP	direct
24 Dec - 28 Dec	Air Canada
15 Dec - 10 Jan	TAP	direct
25 Dec - 04 Jan	Icelandair
26 Dec - 05 Jan	British Airways
27 Dec - 01 Jan	Turkish Airlines

Also check the deals for one-way flights from Washington to Lisbon 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 Lisbon in December from $532

Return flights