AirHint found the following cheapest one-way flights from Seattle (SEA) to Helsinki (HEL) in August 2025 (see full year).

One-Way flights

18 Aug	Icelandair
10 Aug	Icelandair
09 Aug	Icelandair
07 Aug	Spirit Airlines
08 Aug	Icelandair
13 Aug	Finnair	direct
18 Aug	Finnair	direct
17 Aug	Finnair	direct
03 Aug	Finnair	direct
04 Aug	Finnair	direct

Also check the deals for return flights from Seattle to Helsinki 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 one-way flights from Seattle to Helsinki in August from 263€

One-Way flights