This cloud is an amazingly efficient weather factory. Nearly 2,000 thunderstorm cells are estimated to be present over the planet at any given time. It is estimated that globally there are 16 million thunderstorms each year. In the United States, central Florida has almost 100 thunderstorm days annually. By comparison the number of thunderstorm days in Wyoming varies across the state from about 20 to 60 per year.
Thunderstorms occur with the greatest frequency in the eastern counties.
This is partly caused by the warmer surface temperatures allowed by the relatively low elevations in this region, but it is primarily the result of the more humid surface air there. Moist air moving across the Great Plains is often too shallow to cross the Laramie Range and the Big Horn Mountains. As a result, the surface air is drier on the west side of these topographic barriers and thunderstorms are correspondingly less common. Moisture from the Pacific Ocean fuels thunderstorms in western Wyoming, but the intervening middle third of the state, and especially the Big Horn Basin area, is relatively protected from thunderstorms by topographic barriers to low-level moisture airflow. Thunderstorms occur most often during the summer months of June, July and August when surface temperatures are highest, reaching a peak in the number of thunderstorm days in July.