Cougar Mountain Trail Run Series (August)

Lace up for an unforgettable trail experience at the Cougar Mountain Trail Run Series (August) on August 8, 2026, in scenic Bellevue, WA. This highly anticipated event, a staple in the Pacific Northwest trail running community, marks the 23rd running of the series and offers distances of 26.2M (marathon), 14.5M, and 3.1M (5K), catering to every level of runner. Held in King County's Cougar Mountain Regional Wildland Park, just 15 minutes from Seattle, the course is a trail running paradise featuring rolling and runnable hills with a diverse range of trails, from narrow and technical single-track to wider, groomed paths. Runners will immerse themselves in lush forests, traverse fern-lined trails, and journey over hills and along picturesque marshes and wetland habitats, with typical race day conditions boasting highs around 78°F and lows around 58°F, and only a 3% chance of precipitation.

The Cougar Mountain Trail Run Series is renowned not only for its beautifully marked courses but also for its vibrant community atmosphere and commitment to local parks. Organized by the Seattle Running Club and Northwest Trail Runs, the series has raised over $265,000 for King County Parks and contributed countless hours of trail work, making each step a contribution to the preservation of these cherished wild spaces. Aid stations will be available along the routes, though participants are encouraged to bring their own refillable water containers as part of the event's "cup-free" initiative. Whether you're aiming for a challenging marathon, a solid long run, or a spirited 5K, the Cougar Mountain Trail Run Series is an excellent opportunity to test your limits, train for a fall ultra, and enjoy the camaraderie of fellow trail enthusiasts, all starting and finishing conveniently at the Sky Country Trailhead.