AirHint found the following cheapest return flights from Seattle (SEA) to Barcelona (BCN) in August 2025 (see full year).

Return flights

24 Aug - 12 Sep	Aer Lingus
24 Aug - 02 Sep	Aer Lingus
25 Aug - 06 Sep	Icelandair
17 Aug - 22 Aug	Icelandair
24 Aug - 13 Sep	Icelandair
24 Aug - 16 Sep	Icelandair
24 Aug - 14 Sep	Icelandair
18 Aug - 25 Aug	Icelandair
21 Aug - 03 Sep	Icelandair
19 Aug - 12 Sep	Icelandair
22 Aug - 29 Aug	Icelandair
25 Aug - 19 Sep	Aer Lingus
20 Aug - 27 Aug	Icelandair
17 Aug - 31 Aug	Icelandair
29 Aug - 13 Sep	Icelandair
05 Aug - 25 Aug	Aer Lingus
05 Aug - 26 Aug	Icelandair
04 Aug - 26 Aug	Aer Lingus
03 Aug - 09 Aug	Icelandair
15 Aug - 17 Aug	Scandinavian Airlines

Also check the deals for one-way flights from Seattle to Barcelona in August.

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 Barcelona in August from 471€

Return flights