Heat Wave in the Eastern US; Heavy Rain in the Ohio Valley

Dangerous, long-lasting heat is expected across portions of the Central and Southeast U.S. Showers and thunderstorms, some severe, may produce heavy rain and localized areas of flash flooding across parts of the Ohio/Tennessee Valleys into the Appalachians. Severe thunderstorms are possible across parts of the northern Great Plains. Fire weather conditions possible in the Great Basin. Read More >

Wet Bulb Globe Temperature

(Prototype -- not official -- availability not guaranteed)

New! Click here for regional and national WBGT forecasts

The Wet Bulb Globe Temperature (WBGT) is a measure of heat stress in direct sunlight, which is based on temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation). This differs from the heat index, also called the apparent temperature, which is based only on temperature and humidity and is calculated for shady areas. If you work or exercise in direct sunlight, the WBGT is a good element to monitor. Scroll down for latest observations and forecasts.