Cheapest return flights from Seattle (SEA) to Denver (DEN), September

Select a price to book. see full year.

Dates, airline, and price
Dates Airline Price
12 Sep 22 Sep Frontier Airlines
Direct Flight
12 Sep 16 Sep Frontier Airlines
Direct Flight
15 Sep 22 Sep Frontier Airlines
Direct Flight
01 Sep 10 Sep Frontier Airlines
Direct Flight
02 Sep 07 Sep Frontier Airlines
Direct Flight
17 Sep 22 Sep Frontier Airlines
Direct Flight
19 Sep 21 Sep Frontier Airlines
Direct Flight
24 Sep 29 Sep Frontier Airlines
Direct Flight
02 Sep 06 Sep Frontier Airlines
Direct Flight
16 Sep 20 Sep Frontier Airlines
Direct Flight
28 Sep 01 Oct Frontier Airlines
Direct Flight
28 Sep 02 Oct Frontier Airlines
Direct Flight
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deals for one-way flights from Seattle to Denver in September.

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Updated Jul 16, 2026.

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