How is the heat index calculated, and why is it more important than the air temperature during some heat waves?

Chicagoans are stepping up to help one another during another heat wave in the city.

A heat advisory goes into effect Thursday for parts of Connecticut where heat index values will soar past 100 degrees on ...

Temperatures will soar to the upper 80s and low 90s Thursday as dew points climb in many areas, making the air feel thick and ...

Northeast Ohio is about to crank up the heat, with dangerous conditions expected Thursday as both temperatures and humidity ...

Thursday: A slight chance of showers and thunderstorms after 2 p.m. Sunny, with a high near 94. Heat index values as high as ...

The heat will be most severe along and southeast of the I-99/US-220 corridor, where heat index values are likely to exceed ...

With heat index values expected to top 110 degrees, Knox County residents are urged to take precautions. Here's where to find ...

A Heat Advisory remains in effect for most North Alabama and Middle Tennessee counties through 9:00 PM CDT as the heat index ...

“Thursday remains on track to be the hottest day of the week; a heat advisory will likely be needed as the heat index reaches ...

Brevard County experienced a heat advisory with a heat index as high as 112 degrees Fahrenheit on July 21. While temperatures ...

Temperatures could soar into the mid-90s to upper 90s, with humidity making it feel as hot as 105 or 106 degrees in some ...