Jun 21, 2024
Clusters of thunderstorms with very high rainfall rates from 2 to 4 inches per hour developed by midday on June 20, and despite being transient, continued to redevelop through the evening and into the overnight hours. The primary focus occurred between Iowa Highway 9 and U.S. Highway 18 as the effective cold pool boundary collapsed southward and locked in place through the night. The final 24 hour rainfall totals reached 6 to 12 inches by daybreak across and near Lyon and northern Sioux counties
Source: NOAA National Weather Service Storm Events Database (event 1197872). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Sioux County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.