The Running Weather Index scores every U.S. city 1–10 for outdoor run conditions — temperature, humidity, wind, cloud cover, and rain scored and weighted for what actually affects your performance.
The Running Weather Index scores each U.S. city from 1 to 10 using National Weather Service NDFD forecast data at 2.5km resolution, updated every morning. Six weather factors are scored and combined into a single composite number that reflects what conditions actually feel like for outdoor running. Humidity carries the most critical weight — high dewpoint limits performance and raises heat risk more than any other variable.
A score of 10 means near-perfect running conditions. A score of 1 means conditions are poor — too hot, too humid, or too wet for a comfortable run. The index covers the contiguous United States with 37,000+ city data points.