Zelus WBGT: Real-Time Heat Safety Monitoring Zelus is a patented system that delivers hyperlocal Wet Bulb Globe Temperature (WBGT) readings, lightning alerts, AQI data, and compliance documentation tools — without expensive weather hardware. WBGT is not the same as temperature or heat index. It accounts for the major environmental factors that affect heat stress, including temperature, humidity, wind, and solar radiation. WBGT is widely used in athletics, military, workplace safety, and heat