Flagstaff, AZ Hail Storm – September 2026

Flagstaff, AZ — Late afternoon into early evening on September 17, 2026, a hail-bearing thunderstorm moved across the Flagstaff metro and produced peak hail to 1.87 inches. The event is concluded and produced multiple radar-detected hail alerts.

What Happened

The storm moved through Flagstaff during the late-afternoon and early-evening hours on September 17, 2026. The National Weather Service issued four hail alerts based on dual-polarization NEXRAD radar detections at these times and sizes (local time):

• September 17 · 4:47 PM MST (23:47 UTC) — 1.26 inches detected by radar.
• September 17 · 4:52 PM MST (23:52 UTC) — 1.00 inch detected by radar.
• September 17 · 5:12 PM MST (00:12 UTC) — 1.57 inches detected by radar.
• September 17 · 5:42 PM MST (00:42 UTC) — 1.36 inches detected by radar.

Radar returns showed a sustained hail signature for roughly one hour as the cell translated across multiple notification zones within the Flagstaff metro. The NWS alerts were driven by dual-polarization radar hail detection. No active warnings remained after the early-evening period; the storm is recorded as concluded.

Damage Assessment

Hail sizes reported by radar in this event fall into the range associated with cosmetic to structural damage on common building materials. Coin-sized and larger hail can dent metal, crack or fracture asphalt shingles, and shatter glazing on skylights or unsecured windows. The event included hail larger than a golf ball (golf ball = 1.75 inches), which raises the likelihood of shingle granule loss, lifted or split fiberglass shingles, and moderate denting of aluminum and steel surfaces.

Vehicles parked outdoors in the Flagstaff metro during the late-afternoon to early-evening period are at risk of door and hood dents, broken mirrors, and cracked or chipped windshields when hail approaches and exceeds golf-ball size. Roof coverings older than 10 years, non-impact-rated skylights, and exposed HVAC equipment are among the most vulnerable assets for this event. Localized impacts reported in field surveys and citizen reports are being compiled against the radar hail track for spatial correlation.

What Contractors Should Know

Prioritize exterior inspections in the Flagstaff metro that focus on roofs, siding, gutters, commercial metal panels, and vehicle fleets. On roofs, inspect for broken or missing granules, split tabs, fractured fiberglass, and any deformation around vents or penetrations. Photograph damage with scale and GPS-enabled timestamps. Record pre-existing conditions and note whether coverings are original or previously repaired.

For immediate field work, secure loose materials and cover exposed interiors only after documenting damage. Avoid permanent repairs until insurance and property owners approve scope. Use caution on elevated surfaces and follow local fall-protection requirements. For vehicle fleets, document dents and glass damage, and segregate units for staged repair or claims processing.