Affordable DEN to SEA Flights: Fly from the Rockies to the Pacific Northwest

To maximize your comfort and savings on the DEN to SEA route, always aim to book your tickets at least three to four weeks in advance, as last-minute business travel often drives up prices significantly. Since both Denver and Seattle are major hubs for Alaska and United, consider joining their frequent flyer programs to earn valuable miles or gain access to lounge upgrades during your journey. For the best aerial photography of Mt. Rainier as you approach Seattle-Tacoma International Airport, try to secure a window seat on the left side of the aircraft. Lastly, remember that Denver's weather can be unpredictable, so check for potential de-icing delays during winter months even if Seattle is forecast to be clear.

Flight prices between Denver and Seattle generally peak during the summer months of June through August, when the weather in Washington is most favorable for hiking and outdoor sightseeing. You will also see a surge in fares during the winter holidays and spring break periods due to increased demand. Conversely, the shoulder seasons of late September and early May typically offer the most competitive rates. If you are looking for the absolute lowest fares, February is often the cheapest month to fly, though you should be prepared for the characteristic drizzle of a classic Seattle winter.