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

A heat wave hit much of the central U.S. over the weekend, while snow and cool temperatures arrived in the Northwest.

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

An AccuWeather forecast map showed states in the "high" risk zone for Friday included parts of Kentucky, Illinois, and Indiana. As the weekend approaches, the severe threat expands further south.