Extreme heat is impacting states across the country. See maps of high temperature forecasts and heat index levels.

A brutal heat wave across the eastern United States trapped millions of people in sweltering air this week with record-high ...

Maps show where extreme humidity and 90- or 100-degree temperatures will affect about 255 million people across the United ...

A heat wave is currently affecting about 160 million people, according to the National Weather Service. Here's which states ...

Several states are expecting extreme heat, with the heat index, or feels-like temperature, surging past 100 degrees.

Climate change has tripled the frequency of atmospheric wave events linked to extreme summer weather in the last 75 years and that may explain why long-range computer forecasts keep underestimating ...