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

Return flights

09 Sep - 17 Sep	SWISS
02 Sep - 17 Sep	Icelandair
03 Sep - 10 Sep	Icelandair
10 Sep - 25 Sep	Scandinavian Airlines
01 Sep - 08 Sep	Icelandair
09 Sep - 16 Sep	Icelandair
30 Sep - 07 Oct	Icelandair
24 Sep - 01 Oct	Icelandair
15 Sep - 19 Sep	Icelandair
19 Sep - 26 Sep	Icelandair
17 Sep - 24 Sep	Icelandair
27 Sep - 21 Oct	Delta
01 Sep - 15 Sep	SWISS
19 Sep - 04 Oct	Scandinavian Airlines
27 Sep - 04 Oct	United

Also check the deals for one-way flights from Seattle to Zurich 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 Zurich in September from 388€

Return flights