Lace up your trail shoes for the Cougar Mountain Trail Run Series on May 9, 2026, offering challenging 10.8-mile and scenic 5.1-mile distances in Bellevue, WA. Nestled just 15 minutes from Seattle, King County's Cougar Mountain Regional Wildland Park provides a trail runner's paradise, renowned for its lush forest, fern-lined single-track trails, and diverse terrain. Runners will navigate rolling hills, moderate climbs, and some steep, short inclines, encountering a mix of narrow, technical sections with roots and rocks, as well as wider, groomed paths through marshes and wetland habitats. The 5.1-mile course features approximately 550 feet of elevation gain, while the 10.8-mile distance climbs around 1900 feet, providing a robust workout amidst beautiful scenery, though without grand panoramas.

This well-established event, now in its 22nd year, is a favorite among local trail runners and is celebrated for its exceptional organization by the Seattle Running Club and Northwest Trail Runs. Participants can expect well-marked trails, a vibrant community atmosphere, and the satisfaction of contributing to a worthy cause, as a portion of every entry directly supports King County Parks, totaling over $265,000 in donations and hundreds of hours of trail work to date. Aid stations along the course are cupless, requiring runners to bring their own refillable hydration containers, and will offer water, Skratch hydration, and basic snacks. Typical race day conditions in early May often see comfortable highs around 65F and lows around 47F, with only a 10% chance of precipitation, creating ideal weather for tackling the varied terrain.

After conquering the trails that are popular training grounds for area trail runners, the experience continues at the Sky Country Trailhead start/finish area. Runners rave about the supportive community and post-race festivities that include food and libations, such as beer from Flying Lion Brewery for those over 21. Whether you're aiming for a personal best on the challenging courses or looking for an engaging run through a beautiful Pacific Northwest wildland park, the Cougar Mountain Trail Run Series promises a rewarding and memorable day for all experience levels.