AirHint found the following cheapest return flights from Seattle (SEA) to Lisbon (LIS) in May 2026 (see full year).
Return flights
| 19 May - 26 May | Aer Lingus | ||
| 21 May - 23 Jun | Air Canada | ||
| 01 May - 01 Jun | Turkish Airlines | ||
| 21 May - 15 Jun | Air Canada | ||
| 21 May - 22 Jun | Air Canada | ||
| 25 May - 08 Jun | Aer Lingus |
Also check the deals for one-way flights from Seattle to Lisbon in May.
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