The temperature on any given summer day may be in the 80s or 90s. So why does it feel so much hotter and oppressive at times? That's the heat index doing its thing. Here's how it works: What is the ...

Extreme levels of heat and humidity are forecast to spread across the country over the next two weeks, blanketing the Southwest, Midwest, and East Coast with high temperatures beginning this June 19 ...

The first major heat wave of summer has enveloped much of the midwestern and eastern U.S. in a brutal “dome” of record temperatures and high humidity. The dome phenomenon happens when weather ...

The first heat wave of summer, starting Friday in central states, will bring days of extreme conditions to many cities across the United States, with humidity levels reaching far beyond what is normal ...