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

Return flights

14 May - 22 May	Turkish Airlines
12 May - 20 May	Turkish Airlines
05 May - 16 May	Turkish Airlines
12 May - 20 May	TAP	direct
05 May - 16 May	TAP	direct
18 May - 27 May	TAP	direct
04 May - 11 May	TAP	direct
21 May - 26 May	TAP	direct
14 May - 22 May	TAP	direct
14 May - 21 May	TAP	direct
25 May - 04 Jun	Royal Air Maroc
25 May - 01 Jun	Iberia
25 May - 04 Jun	TAP	direct
25 May - 01 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 $600

Return flights