Isabel, SD Hail Storm – September 2026

Isabel, SD experienced a severe hail-producing thunderstorm in the late afternoon and early evening of September 5, 2026. The storm produced large hail and a sequence of radar-detected NWS alerts along a defined warning area.

What Happened

The event unfolded late afternoon into early evening on September 5, 2026. NWS-issued alerts for this storm arrived in eight updates as the cell moved through the Isabel area. The alert sequence and reported hail detections were:

• September 5 · 4:17 PM CDT (21:17 UTC) – 1.90 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 4:32 PM CDT (21:32 UTC) – 1.65 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 4:45 PM CDT (21:45 UTC) – 1.75 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 4:56 PM CDT (21:56 UTC) – 1.25 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 5:21 PM CDT (22:21 UTC) – 1.00 inch hail – NWS warning only (warning area)
• September 5 · 5:44 PM CDT (22:44 UTC) – 1.22 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 6:09 PM CDT (23:09 UTC) – 1.24 inch hail – dual-polarization radar (NEXRAD hail detection)
• September 5 · 6:25 PM CDT (23:25 UTC) – 1.93 inch hail – dual-polarization radar (NEXRAD hail detection)

Most updates were driven by dual-polarization radar detection. One update was issued as an NWS warning area with the size estimate noted in the warning text. This page aggregates those multi-zone alerts for the Isabel metro.

Damage Assessment

Radar-detected hail in the 1.0–2.0 inch range typically causes cosmetic to functional damage on vehicles and can bruise or perforate softer roofing materials. Reports in this sequence include multiple radar-detected hail signatures at and above golf-ball size (1.75 inch). Hail of this scale commonly dents metal panels, cracks plastic trim, and strips roofing granules.

Hail approaching or exceeding baseball size (2.75 inch) presents a greater risk to roof decking, skylights, soffits, and unshielded mechanical equipment. Roof shingles can fracture; clay and concrete tiles can crack. Occupied vehicles left outside are at high risk for severe panel and glass damage. Structures with older or weathered coverings are more likely to show immediate, visible impact.

What Contractors Should Know

First-response teams should prioritize safety and triage. Confirm scene access with property owners and local authorities before mobilizing. For initial inspections, document damage location, take high-resolution photos of roofing, siding, HVAC units, and vehicles, and note preexisting wear. Focus first on identifying breached waterproofing and exposed roof decking that create immediate water intrusion risk.