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

Return flights

28 Sep - 09 Oct	Condor	direct
21 Sep - 07 Oct	Condor
17 Sep - 24 Sep	Condor
18 Sep - 02 Oct	Condor
08 Sep - 26 Sep	Condor
08 Sep - 26 Sep	Condor	direct
12 Sep - 25 Sep	Condor
21 Sep - 07 Oct	Condor	direct
08 Sep - 15 Sep	Condor
10 Sep - 23 Sep	Condor
30 Sep - 06 Oct	Condor
23 Sep - 04 Oct	Condor
08 Sep - 04 Oct	Condor
12 Sep - 19 Sep	Alaska Airlines
19 Sep - 30 Sep	Condor
28 Sep - 12 Oct	Condor	direct
11 Sep - 18 Sep	Condor
09 Sep - 04 Oct	Condor
27 Sep - 10 Oct	Turkish Airlines
13 Sep - 26 Sep	Turkish Airlines

Also check the deals for one-way flights from Seattle to Frankfurt 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 Frankfurt in September from 512€

Return flights