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

Return flights

23 Sep - 16 Oct	Aer Lingus	direct
30 Sep - 08 Oct	Aer Lingus	direct
21 Sep - 07 Oct	Aer Lingus	direct
30 Sep - 07 Oct	Aer Lingus	direct
15 Sep - 26 Sep	Delta
26 Sep - 18 Oct	Scandinavian Airlines
17 Sep - 04 Oct	Air Canada
18 Sep - 25 Sep	Aer Lingus	direct
20 Sep - 25 Sep	Aer Lingus	direct
19 Sep - 24 Sep	Delta
27 Sep - 11 Oct	Delta
08 Sep - 15 Sep	jetBlue
18 Sep - 04 Oct	Delta
20 Sep - 28 Sep	United
18 Sep - 11 Oct	United
16 Sep - 22 Sep	Aer Lingus
08 Sep - 24 Sep	Icelandair
08 Sep - 16 Sep	Alaska Airlines
25 Sep - 18 Oct	Turkish Airlines
08 Sep - 18 Sep	Air Canada

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

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 Seattle to Dublin in September from 397€

Return flights