Answer: Thunderstorms

Heat bursts are such a rare occurrence that there’s a very good chance that anyone reading this bit of atmosphere-focused trivia today will never experience one in their lifetime, and if they do, it likely won’t be (thankfully) one of the real record setters.

A heat burst, as the name implies, is an intense burst of heat that scientists believe are caused, in incredibly rare instances, by the decay of a thunderstorm. The theory goes that when rain evaporates into a pocket of cold dry air high above it in the atmosphere, the rapid change in air density causes the pocket of air to drop quickly, compressing the air beneath it. This rapid compression causes an increase in air temperature and if the mass of the now-dense high altitude air is enough to carry it down to the ground where we’re all milling about, then we get the joy of experiencing a significant spike in air temperature out of the blue.

On the low end of the scale, it can cause bizarre swings in temperature like a cold rainy day suddenly (and briefly) becoming unbearably hot. On the more extreme end of the scale, however, the ambient temperature can suddenly rise to well above a hundred degrees. While there have been dozens of examples of mild heat bursts recorded over the last two centuries (mild as in the temperature jumps from, say, 70F to 90F for an hour or so), there have been some extreme cases of the heat spiking well above 120F. In Cherokee, Oklahoma in 1909 and in Kopperl, Texas in 1960, for example, heat bursts pushed the temperature so high that it killed crops in the field like they had been left to bake in an oven.