Concerning high temperature records, the days Pittsburgh will be closest to record highs will be Monday (95F set in 1894) and Tuesday (96F set in 1882). DuBois, Pa., and Morgantown, West Virginia, which are other sites in our coverage area that keep long-term climate records, may also break record highs from Monday to Wednesday.

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.

An excessive heat warning is set to be in effect at noon across most of Minnesota, while the rest of the state is under a heat advisory.