Cheapest return flights from Seattle to Lisbon in September from $622

AirHint found the following cheapest return flights from Seattle (SEA) to Lisbon (LIS) in September 2025 (see full year).

Return flights

23 Sep - 29 Sep Air Canada
27 Sep - 05 Oct Icelandair
23 Sep - 30 Sep Aer Lingus
22 Sep - 06 Oct Turkish Airlines
30 Sep - 25 Oct Turkish Airlines
18 Sep - 11 Oct Turkish Airlines
20 Sep - 02 Oct Aer Lingus
17 Sep - 23 Sep WestJet
13 Sep - 04 Oct Hawaiian Airlines
10 Sep - 17 Sep Hawaiian Airlines
22 Sep - 13 Oct United
17 Sep - 20 Sep Hawaiian Airlines
08 Sep - 15 Sep Alaska Airlines
08 Sep - 30 Sep Turkish Airlines

Also check the deals for one-way flights from Seattle to Lisbon in September.

Skyscanner

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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