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

Return flights

16 Sep - 18 Sep	Condor
10 Sep - 17 Sep	Air Canada
24 Sep - 08 Oct	Condor
16 Sep - 18 Sep	Condor	direct
28 Sep - 10 Oct	Condor	direct
17 Sep - 24 Sep	Condor
09 Sep - 16 Sep	Condor
30 Sep - 07 Oct	Condor
24 Sep - 01 Oct	Condor
29 Sep - 15 Oct	Condor
23 Sep - 30 Sep	Condor
24 Sep - 08 Oct	Condor	direct
22 Sep - 29 Sep	Condor
27 Sep - 08 Oct	Condor
07 Sep - 14 Sep	Condor
15 Sep - 22 Sep	American Airlines
12 Sep - 19 Sep	Condor
23 Sep - 04 Oct	Condor
29 Sep - 06 Oct	Condor
25 Sep - 06 Oct	Condor

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 $520

Return flights