The Extech HT30 heat stress WBGT meter measures how hot it feels by considering temperature, humidity, air movement, and radiant heat. It measures wet bulb and air temperatures from 0 to 50°C with 1.1°F accuracy, and relative humidity from 0–100% with 3% accuracy. Black Globe Temperature monitors direct solar radiation on an exposed surface. An in/out function displays WBGT value with or without direct sun exposure. A built-in RS-232 interface allows connection to optional PC software for data logging.