It's because of something called the heat index. The heat index measures what the air temperature combined with the level of humidity feels like to the human body, the National Weather Service says.

Experts share advice on how to stay cool and safe amid weather alerts - Heat poses a health risk, especially for children, ...

Summer is just getting started, and millions of people are under heat advisories as a major heat wave spreads across large ...

And when high humidity happens in conjunction with high temperatures and intense sun, it poses an even bigger threat. One measurement of that risk comes via the “wet bulb” temperature forecasts.

Humidity will soon surge to extreme levels across 40 states. Find out where there will be excessive heat and humidity — and ...

The southern stretch of Alabama is heating up fast. By Saturday, June 7, the city will move into the danger zone on the heat index. By Sunday, the extreme heat is forecast to spread east along the ...