Methodology

How the Run Score works

By Iustin Nita · Updated July 21, 2026

The Run Score is a 0-100 rating of how good the weather is for running. RunWeather computes it from estimated wet-bulb globe temperature (WBGT), dew point, air temperature, wind, precipitation, UV, air quality, daylight, and visibility, then blends three sub-scores, performance (50%), safety (35%), and experience (15%), and caps the result whenever conditions cross a safety line. Every threshold the model uses is published on this page.

What do the score bands mean?

The same tier table drives the app, the free calculator, and the live heat-risk board, so a 78 always means the same thing everywhere.

How is the score calculated?

The model (v4) is anchored on estimated WBGT (the heat-strain metric race directors use to flag risk) rather than air temperature or a "feels like" number. WBGT combines temperature, humidity, sun exposure, and wind into one measure of how hard your body must work to shed heat. From the full forecast, RunWeather derives a pace-adjustment estimate (how much conditions should slow you at even effort), a safety evaluation, and a comfort/experience read, then blends them 50/35/15 into the headline score. The model's research basis includes ACSM heat-safety guidance (Mantzios et al., 2022) and NOAA/NWS WBGT and wind-chill references.

What dew point is too high for running?

Dew point, not relative humidity, decides how well sweat evaporates. RunWeather scores it in five bands; above 70°F (21°C) the air is oppressive for running, and 81°F (27°C) is a hard safety gate regardless of fitness.

What temperature is ideal for running?

Peak performance sits at 50°F (10°C) to 54°F (12°C) air temperature. Above 59°F (15°C) the model reads warmth as working against you, above 77°F (25°C) it reads as hot, and above 86°F (30°C) heat becomes the dominant limiter. Cold slows you less than heat: performance holds well below 41°F (5°C), and the danger in winter is wind chill, not the thermometer.

How does wind change the score?

A light 1 mph-4 mph (2-7 km/h) breeze actually helps by aiding evaporative cooling, so the scoring plateau sits there rather than at dead calm. Wind resistance becomes noticeable around 7 mph-9 mph, strong at 12 mph, and gusty above 16 mph. RunWeather scores gust-effective wind, not just the sustained number, because gusts break rhythm and slow you more than their average suggests. In the cold, wind drives the wind-chill governor instead.

When does RunWeather flag a run as unsafe?

Safety gates cap the score no matter how good everything else looks. Standard limits relax slightly for heat-acclimated runners; hard limits never do.

WBGT heat-stress tiers used across the app and the live heat-risk board: moderate from 64°F (18°C), high from 73°F (23°C), extreme from 82°F (28°C). Thunderstorms, hazardous air quality (AQI 200+), and very low visibility also gate the score directly.

Is the score personalized?

Yes. The published thresholds are the defaults; the app then adapts to you: heat acclimatization built over 10-14 days of warm-weather running raises your effective heat tolerance, and runners who sync Strava get personal thresholds learned from how conditions actually affected their pace and heart rate on past runs.

Where can I see the Run Score?

In the RunWeather app for iOS and Android (scored hour by hour with the best window to run), in the free Run Score calculator for any location, and on the hourly Heat Risk Today board. The calculator and the app run the exact same scoring engine, so the numbers always match. For how specific conditions feel in practice, see the guides on heat, humidity, cold, and wind.