Since 1901, the portion of annual precipitation falling during the heaviest one percent of rain events has increased substantially. Research suggests that this trend will continue, resulting in more frequent and intense extreme precipitation events that will have social, economic, and ecological impacts across the state.

This map shows southern and western Wisconsin are more susceptible to extreme rainfall events.
This map shows 100-year rainfall and 2010-2020 extreme events in Wisconsin. Notes: The extreme rainfall events are the largest independent events that exceeded the 100-year threshold. If an extreme event was recorded at numerous locations, only the largest recorded value was showed. Any two-day events were classified by their largest value recorded. Source: Center for Climatic Research, Nelson Institute for Environmental Studies, UW-Madison. Data: UWPD Downscaled Data. View a larger version of this graphic

In June of 2008, after nearly seven inches of rain in 24 hours, the dam that held Lake Delton broke, causing millions of dollars of property damage and disrupting the tourist season in the Wisconsin Dells area. That storm impacted nearly half of Wisconsin’s counties and caused more than $750 million in damage statewide. Similar events have struck across the state: 2018 flooding in the Kickapoo River Valley and the destruction of the Saxon Harbor Marina in Iron County in 2016.

Extreme precipitation also impacts agriculture, as heavy rains in the spring and summer can cause damage to newly planted fields and delay harvest in the fall. The timing of these heavy rains may also contribute to more rain on frozen ground, degrading water quality, and reducing soil moisture. To succeed, farmers will have to adapt to changes in heavy rainfall patterns.

As the people of Wisconsin adapt to more frequent, heavier precipitation events, we present research detailing likely future precipitation changes, adaptation efforts, and ecological, social and economic con-sequences of the increasing frequency, and intensity of these events.

Key Points

Learn More About Extreme Precipitation Research at UW-Madison

Additional Resources