Pacific Northwest Race Calendar: Your Guide to Seattle-Area Events

Find Half Marathons, 10Ks, 5Ks, and Charity Races Throughout Washington State

The Pacific Northwest offers year-round racing opportunities with stunning scenery—from waterfront races along Puget Sound to mountain views and forest trails. The Seattle area hosts everything from major city marathons to intimate community 5Ks. The historic Mercer Island Half Marathon exemplified this region's running tradition, and today countless events continue bringing runners together for competition, community, and charitable causes.

Spring Racing Season: March - May

Spring race with blooming cherry blossoms and runners

Spring represents prime racing season in the Pacific Northwest as weather improves and training through winter pays off. Comfortable temperatures and blooming scenery create ideal conditions for personal records.

Historic Spring Events

Mercer Island Half Marathon (late March tradition for 45+ years) - Though no longer running, this event's legacy lives on in the running community it fostered. Many former participants continue racing at other spring half marathons.

Spring Racing Highlights

  • Seattle Marathon Spring Training Series: Multiple tune-up races preparing for fall marathons
  • Mercer Island 5K/10K Community Runs: Various charity events on the island
  • Lake Sammamish Half Marathon: Scenic Eastside course
  • Kirkland Shamrock Run: St. Patrick's Day themed race
  • Various charity runs: Cancer awareness, children's hospitals, local causes

Spring Advantages

  • Training through winter pays off with peak fitness
  • Cool temperatures ideal for distance running
  • Cherry blossoms and spring flowers make courses scenic
  • Momentum builds toward summer trail season

Major organizer: Seattle Marathon Events

Summer Trail and Mountain Races: June - August

Summer racing in the Pacific Northwest shifts to trails and mountains, escaping city heat for cooler alpine environments. These challenging races showcase the region's spectacular natural beauty.

Mountain Race Options

  • White River 50K: Cascade mountain ultra marathon
  • Mount Si Trail Half Marathon: Challenging elevation with stunning views
  • Cougar Mountain Trail Run Series: Regular trail races on Eastside
  • Bellingham Bay Marathon: Coastal Pacific Northwest beauty
  • Various trail 10Ks and 5Ks: Beginner-friendly trail introductions

Summer Racing Benefits

  • Long daylight hours for early morning/evening races
  • Alpine scenery and mountain vistas
  • Cooler temperatures at elevation
  • Adventure racing atmosphere
  • Technical terrain builds strength

Note: Popular summer trail races fill months in advance—register early!

Trail running resources: Trail Runner Magazine

Trail runner on mountain path with Cascade peaks background

Fall Racing Prime Time: September - November

Fall race with autumn leaves and golden colors

Fall brings Seattle's biggest races and ideal racing conditions. Cool, overcast Pacific Northwest weather creates perfect conditions for personal records.

Major Fall Events

  • Seattle Marathon & Half Marathon: Thanksgiving weekend tradition with thousands of participants
  • Rock 'n' Roll Seattle Half Marathon: Music-themed race through city
  • Bellevue 10K: Popular Eastside race
  • Kirkland Half Marathon: Waterfront course on Lake Washington
  • Tacoma City Marathon: South Sound racing

Fall Racing Advantages

  • Cool temperatures perfect for PRs
  • Summer training block creates peak fitness
  • Stunning fall foliage on courses
  • Largest participant fields create race energy
  • Goal race timing for many runners

Popular Race Sizes

Seattle Half Marathon: 10,000+ runners
Rock 'n' Roll Seattle: 8,000+ participants
Various smaller races: 500-2,000 participants

Winter Running: December - February

Determined runners in rain gear during winter race

Winter racing in the Pacific Northwest means embracing rain and cold, but offers unique experiences and dedicated running community camaraderie.

Winter Race Options

  • Resolution runs: New Year's Day races (5K, 10K options)
  • Holiday charity runs: December events supporting local causes
  • Small community races: Dedicated runner fields
  • Winter training series: Preparation for spring goals
  • Virtual race options: Flexibility for Pacific Northwest weather

Winter Racing Benefits

  • Builds mental toughness for spring races
  • Smaller, community-focused events
  • Less crowded courses
  • Prime training season maintains fitness
  • Tests gear and weather strategies

Winter Considerations

Pack waterproof gear, wear layers, use reflective clothing for dark mornings. Many winter races offer shorter distances accommodating weather conditions.

Plan Your Racing Year

The Pacific Northwest offers year-round racing opportunities for every runner. Register early for popular races—many sell out months in advance, especially fall goal races and summer trail events. Create your yearly racing schedule balancing goal races with fun community events. Use spring and fall for peak performances, summer for adventure, and winter for building the foundation for next season. Every race connects you to the vibrant Pacific Northwest running community that the Mercer Island Half Marathon helped foster for over 45 years.

Training Plans

Find races: RunSignUp Washington | Running USA Calendar