The WetBulb Globe Temperature (WBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). This differs from the heat index, which takes into consideration temperature and humidity and is calculated for shady areas.
WBGT SD Card Logger - 800037
WBGT Meter with Color-Coded LCD - 801038
WBGT Heat Stress Meter - 800036