Sunday morning at around 4:30 A.M. CDT, Sioux Falls, SD reached an "Africa Hot" temperature of 101F after being in the 70s just 10 minutes prior! Why? The cause was a convective heat burst created by a collapsing thunderstorm 10 to 20K feet above ground level. These heat burst exist where rain from storms falls through a dry air mass. This dry air mass allows the rain to evaporate which cools the air and allows it to fall faster. As the air falls to Earth it warms at about 10C per 1KM due to compressional heating. If the falling air builds enough momentum it will reach the ground and cause a heat spike of up to about 30F in just a few minutes. Below is the RUC forecast sounding for Sioux Falls, SD valid 4 A.M. (courtesy of NOAA NWS).

These heat bursts are not rare; nevertheless it is "cool" when it happens. Below is the temperature and dewpoint timeline for the automated surface observation system (ASOS) at Joe Foss Field (provided by NOAA NWS). Notice the rapid temperature rise and and the plummeting dew point.