AirHint found the following cheapest return flights from Washington (IAD) to Lisbon (LIS) in May 2026 (see full year).

Return flights

18 May - 25 May	TAP	direct
15 May - 26 May	TAP	direct
02 May - 19 May	TAP	direct
10 May - 17 May	TAP	direct
07 May - 30 May	Turkish Airlines
09 May - 30 May	Turkish Airlines
19 May - 26 May	TAP	direct
18 May - 13 Jun	TAP	direct
27 May - 07 Jun	Royal Air Maroc
09 May - 30 May	TAP	direct
07 May - 30 May	TAP	direct
23 May - 31 May	Icelandair
22 May - 13 Jun	Royal Air Maroc
24 May - 03 Jun	Scandinavian Airlines
22 May - 13 Jun	TAP	direct
27 May - 07 Jun	TAP	direct
23 May - 02 Jun	TAP	direct

Also check the deals for one-way flights from Washington to Lisbon in May.

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 May from 530€

Return flights