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

Return flights

10 Sep - 26 Sep	Air Canada
10 Sep - 18 Sep	Air Canada
30 Sep - 07 Oct	Aer Lingus	direct
30 Sep - 08 Oct	Aer Lingus	direct
12 Sep - 17 Sep	Air Canada
11 Sep - 14 Sep	Aer Lingus	direct
28 Sep - 05 Oct	Icelandair
09 Sep - 04 Oct	Air France
16 Sep - 21 Sep	Air Canada
12 Sep - 20 Sep	Air Canada
09 Sep - 04 Oct	Aer Lingus	direct
13 Sep - 28 Sep	SWISS
27 Sep - 11 Oct	Delta
13 Sep - 20 Sep	Air France
16 Sep - 22 Sep	SWISS
16 Sep - 19 Sep	Aer Lingus
18 Sep - 11 Oct	Aer Lingus	direct
27 Sep - 11 Oct	Aer Lingus	direct
24 Sep - 18 Oct	Scandinavian Airlines
26 Sep - 03 Oct	Aer Lingus	direct

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 $427

Return flights