Wettest counties in Illinois

Rain, sleet, snow, hail, wintry mix. Precipitation takes on many forms, and the degree to which climate change affects precipitation levels comes down to something almost everyone learns about in school—Earth's water cycle. A system in endless motion, the water cycle traces the process through which water exists in its three primary phases—liquid, solid, and gas—as it moves perpetually between the Earth and its atmosphere.

Increases in precipitation frequency and intensity are markers of climate change. When temperatures rise and oceans grow warmer, the amount of water that evaporates into the atmosphere—and the speed at which it does so—also increases. As atmospheric circulation carries the moisture-rich air over land or pushes it into a storm system, heavy rain or snow is often the result.

The continental U.S. on average received about 30 inches of precipitation between March 2022 and February 2023. Traditionally "wet" regions—such as Washington state and Alaska in the northwest and Georgia and Mississippi in the southeast—continue to have some of the rainiest counties in the United States. Other areas such as Oklahoma, Kansas, and Nebraska, as well as pockets of the South and of California, experience the opposite extreme: drought, also largely a product of climate change.

Stacker cited data from the National Centers for Environmental Information to identify the counties in Illinois that receive the most precipitation through rain, sleet, or snow. Counties are ranked by five-year precipitation averages in inches as of February 2023 with rainfall over the past year serving as a tiebreaker. Supplementary data on how last year's precipitation compares to the 100-year average for the area is also included.