Cheapest return flights from Seattle to Lisbon in September from $596

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

Return flights

27 Sep - 05 Oct Icelandair
05 Sep - 02 Oct Icelandair
06 Sep - 02 Oct Icelandair
09 Sep - 23 Sep Aer Lingus
10 Sep - 17 Sep Turkish Airlines
24 Sep - 09 Oct Turkish Airlines
04 Sep - 07 Sep Icelandair
17 Sep - 27 Sep Turkish Airlines
05 Sep - 06 Sep Air Canada

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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