Southeast Wisconsin experienced severe flash flooding from Saturday, August 9 into Sunday, August 10, 2025, as torrential rainfall overwhelmed the region. Some areas reported rainfall totals exceeding 13 inches within a few hours, setting historic records. Milwaukee County alone received over six inches of rain, with Butler and parts of Milwaukee's Florist Avenue seeing up to 10 and 13 inches respectively. This unprecedented volume of rain caused widespread submergence of roads, leaving highways like Interstates 43, 41, and 94 underwater, severely disrupting transportation. Mitchell International Airport was also heavily affected, with all but one runway flooded, forcing flight cancellations and diversions.

The flooding significantly disrupted daily life and events in the area. The Wisconsin State Fair was forced to close early, canceling major attractions such as the Lynyrd Skynyrd concert as rising waters inundated the fairgrounds. Dozens of homes reported basement flooding, while crucial infrastructure faced damage with road collapses reported near Menomonee Falls and widespread street flooding across Milwaukee and Waukesha counties. Emergency responders were stretched thin due to hundreds of flood-related calls, and officials urged residents to avoid flooded roads and use non-emergency lines for assistance whenever possible. Several families and individuals were stranded by the rapidly rising waters, with rescue operations ongoing overnight.

Infrastructure across the area was severely tested by the floodwaters. Major highways and bridge structures suffered damage, including a collapse of Lilly Road near Good Hope Road in Menomonee Falls. The Wisconsin Department of Transportation reported multiple highway ramp closures, severely limiting access in and out of flooded zones. Power outages plagued much of the region, affecting over 38,000 We Energies customers, delaying recovery efforts. Additionally, localized river flooding occurred, with the Fox River in Waukesha County surpassing danger levels, exacerbating the flooding threats. Throughout the night, the National Weather Service extended flash flood warnings multiple times due to ongoing heavy rainfall and flood risks.

Authorities issued repeated warnings to stay off flooded roads due to the life-threatening dangers associated with driving through floodwaters. The National Weather Service emphasized that most flood-related deaths occur in vehicles attempting to cross flooded areas. Despite warnings, numerous vehicles became stranded, and water rescues were necessary across metro Milwaukee and surrounding counties. Fortunately, by Sunday morning, dry air began moving into the region, providing cautious relief. However, officials stressed the importance of continued vigilance, particularly in low-lying areas prone to additional flooding or damage from runoff.