A powerful storm system swept through Northwest Iowa and the broader Siouxland region on the evening of Sunday, May 17, 2026, producing multiple funnel clouds, reported tornadoes, and damaging wind gusts of 60 to 70+ mph. Large hail accompanied the storms in several areas, and widespread power outages were reported across Sioux County and surrounding communities as of Monday morning.
The Lyon County Courthouse in Rock Rapids was struck by lightning during the storm system, with damage still being assessed by county officials as of Monday, May 18. A road closure near Maurice, in Sioux County, was also put in place following storm-related impacts to the roadway.
The Storm Prediction Center issued a Tornado Watch for portions of Northwest Iowa into Monday, May 18, with forecasters warning of an additional round of severe weather possible during the day. The primary threats included damaging wind gusts, large hail greater than one inch in diameter, and the possibility of an embedded tornado or two.
Residents across Siouxland were urged to monitor local forecasts and be prepared for continued hazardous conditions. Power restoration crews were deployed across the region, though full restoration timelines were not immediately available.
The storms followed a stretch of dry, favorable fieldwork weather that had allowed Iowa farmers to make significant planting progress during the prior week.