Seattle Marathon
Race Day Weather
Cool start, moderate humidity
Runners will face a temperature trend from 35°F at the start to a high of 42°F. With an average humidity of 78% and light winds from the SE at 5 mph, conditions will be comfortable but may feel cooler. Runners should dress in layers and consider hydration strategies, especially as temperatures rise.
Pace Calculator
Enter a finish time to see what race day does to it.
Get forecast alerts for Seattle Marathon
We'll text or email you when the forecast shifts — so you can adjust gear, pacing, and strategy. Max one per day.
Get your personalized Seattle Marathon race plan
A mile-by-mile breakdown of where your time goes, weather-adjusted splits, fueling timeline with aid stations, packing checklist, carb tracker, spectator guide, all built around your goal and race-day conditions.
Race Info
The Seattle Marathon starts at Seattle Center and finishes at Bell Harbor Pier 66 on the downtown waterfront. A new course introduced for the 2025 race takes runners north along Lake Union's Eastlake shore, across the Montlake Bridge, and through Interlaken Park into the Washington Park Arboretum and the University of Washington campus, then west past Gas Works Park and through Fremont before finishing on the waterfront. First run in 1970 by a group of University of Washington friends, it's the oldest marathon in the Pacific Northwest and still pairs a half marathon with the full on race morning.
