Marengo, IA Hail Storm – March 2025

What Happened

Marengo, Iowa, saw multiple rounds of severe hail on March 19, 2025, with the largest verified stones reaching 1 inch. The storm was active from before daybreak into mid-morning, and four NWS alerts tracked the hail threat across the area.

The first alert came at 4:44 AM CDT, when dual-polarization radar indicated 1-inch hail. A second alert followed at 5:30 AM CDT with radar and spotter verification. Later rounds developed near daybreak and into the morning, with additional alerts at 8:57 AM CDT and 9:10 AM CDT, both tied to 1-inch hail and spotter-confirmed confidence.

Field reports tightened the timeline. At 9:05 AM CDT, a spotter reported hail coming down heavy right then, with stones measured at 1 inch. Two minutes later, another observer described a mix of pea to half-inch hail with hail covering the ground, while a second 9:05 AM CDT report noted pea to half-inch hail at 0.5 inch. The reports place the strongest surface impact in the mid-morning window rather than the first alert cycle.

Damage Assessment

The ground reports point to a storm that produced repeated hail bursts, not a single isolated pulse. Hail coverage was enough to collect on the ground in at least one report, and the size range shifted quickly from pea to half-inch stones up to verified 1-inch hail within minutes.

That pattern fits a compact hail core moving through the warning area in waves. The early radar signal at 4:44 AM CDT showed the threat before spotters confirmed the morning rounds. By 5:30 AM CDT, the storm had enough support from both radar and observers to hold 1-inch hail confidence. The later 8:57 AM CDT and 9:10 AM CDT alerts show the hail threat remained organized into the morning.

No specific structural or vehicle damage was included in the reports provided for Marengo. The available field data does show enough hail coverage to warrant inspection of exposed surfaces, roof edges, gutters, and soft metal trim where repeated 0.5-inch to 1-inch stones can leave marks without producing obvious breakage.

What Contractors Should Know

Marengo sits in east-central Iowa along the corridor where spring hail can arrive before many crews are fully mobilized. This event began before sunrise and continued through mid-morning, so the first inspection window should focus on early-activity properties that may not have received a separate follow-up report after the later hail rounds.

The spotter notes suggest a hail swath with quick size changes across a short time span. One report showed 1-inch hail at 9:05 AM CDT. Another at 9:07 AM CDT fell back to pea to half-inch hail with ground cover. Contractors should treat those transitions as a sign to check adjacent roofs and elevations, not just the address tied to the strongest report.

For exterior triage, start with soft metals, downspouts, gutters, vents, shingles, and skylights. On light commercial roofs, check membrane seams and penetrations near the areas where hail would have built enough coverage to be noticed at ground level. On residential work, look for bruising at roof edges and slope breaks where repeated hail often leaves the most visible pattern.