This animation illustrates how a warming climate changes the frequency of extreme heat. The mountain-shaped line represents how often a temperature of a given value occurs. In both the cooler and the warmer climate, very cold (left side) and very hot (right side) temperatures occur much less frequently than temperatures near the location's average (the high point of the line). But even a small increase in average temperature can cause temperatures that were once extremely rare to become much more common—while also making a location's hottest observed temperatures even hotter. Image by Climate Central.