Wet Bulb Globe Temperature (WBGT)

The core of the Heat Stress score uses WBGT, the gold standard metric used by the NCAA, U.S. Military, and OSHA. WBGT accounts for temperature, humidity, wind speed, and solar radiation. Calculated using the Stull (2011) wet-bulb approximation and Liljegren globe temperature model: WBGT = 0.7 x Tw + 0.2 x Tg + 0.1 x Td

Air Quality Index (AQI)

AQI data from OpenWeatherMap's SILAM atmospheric model (Finnish Meteorological Institute). Scoring follows EPA breakpoints calibrated for respiratory impact during exertion.

UV Exposure

UV index estimated from solar zenith angle modified by cloud cover, following WHO/WMO standard formulas. Amplified for exposed athletic fields.

Field & Turf Conditions

Water balance model: precipitation adds moisture; evapotranspiration (temperature, humidity, wind, solar) removes it. Wet turf elevates slip-and-fall risk.

Storm Risk

Derived from cloud cover, wind gusts, pressure trends, and precipitation. South Florida's convective thunderstorms pose the highest acute risk.

Recommended Exercise Duration

Based on NIOSH/OSHA work-rest guidelines mapped to WBGT thresholds. Durations indicate continuous moderate-intensity exercise before a mandatory rest break.

Composite Score

Score = 0.6 x WeightedAvg + 0.4 x MaxFactor ensures any single extreme factor properly elevates overall risk indication.

Data Sources

Weather: OpenWeatherMap API (10-min updates). Air quality: SILAM model. UV: Solar position + cloud adjustment. All client-side, zero server dependency.