Basically, when the body sweats, the perspiration evaporates, cooling the body. When the humidity is high, the sweat doesn't evaporate as quickly and the body doesn't cool itself as well. Therefore, the body feels warmer. The heat index represents the heat you're feeling outside.

Things will stay hot on Wednesday in Phoenix, as our high will be about 112°F. Highs will stay over 110 degrees for the rest of the work week. By Sunday, we'll see extreme heat relief with a high in the low-100s.

Arizona’s extreme heat isn’t letting up, and daytime highs in the Valley will range from 110 to 116 degrees every day through Friday.