Hail in Calvin · Sep 7, 2026
The estimated-size surface reached 0.75" aloft; NEXRAD logged no point detections over Calvin that day. Open it on the live map to see the swath over the streets.
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Convective day · Sep 7, 2026 · noon–noon UTC
Severity
The 4th most severe storm Calvin has seen in the last 12 months
Overview's storm severity score weighs hailstone size, homes in the footprint, and ground-truth reports.
- Peak hail signal
- 19 /100
- Homes exposed
- 30 /100
- Ground truth
- 0 /100
Largest radar-indicated size — a signal of damage potential, not confirmation.
How many homes sit inside the storm's footprint.
Independent storm reports filed with the NWS.
Evidence / storm surfaces
How Calvin saw the hail — from two instruments
We map this storm two ways: the NEXRAD radar signatures the storm produced overhead, and the radar-estimated size of the hail in the air. The two surfaces don’t have to match — where they diverge is where estimated size aloft ran ahead of, or behind, what the signatures caught.
Estimated size field Maximum hail size as estimated from radar aloft. Treat it as the storm's ceiling — the largest supportable stone — rather than a ground measurement.
Only the radar-estimated size surface resolved for Sep 7, 2026 — this storm produced no NEXRAD point detections over Calvin, so there is one map to show, not two.
The storm in context
Where Sep 7, 2026 sits in Calvin's hail record.
This was Calvin's 5th recorded hail day, arriving 60 days after the Jul 9, 2026 storm. By severity it ranks 4th of the 5 storms we have logged here. Radar put the day's largest stone over Calvin at 0.75" — radar-estimated size aloft.
The Sep 7, 2026 convective day was bigger than Calvin: the same system put hail over 163 other tracked cities, 44 of them in North Dakota. Nearest: Starkweather (28 miles south, up to 0.5"); Rolla (36 miles west, up to 0.5"); Cando (36 miles southwest, up to 0.5").
These maps are stills. In the app this date is one of 5 Calvin storm dates on a live map — both surfaces, the reports, and a replay — and the same map is where you draw the swath. This page rebuilds nightly.
Ground reports
What people on the ground reported
These are storm reports filed with the National Weather Service and released through the NOAA Storm Prediction Center — public-domain observations from spotters, the public, and NWS surveys. We quote each one exactly as filed.
No ground reports were filed with the National Weather Service for this storm over Calvin. That is common: a report depends on someone being there to see it and take the time to call it in. The radar surfaces above are the record here — the storm was detected from above even though no one on the ground logged it.
Near the severe threshold
What 0.75" hail means for Calvin roofs.
A signal this size sits near the National Weather Service severe threshold. Aging shingles and soft metals such as vents, flashing, and gutters may be more vulnerable; roof age, wind, and material condition all matter, and only an inspection can confirm damage.
Radar reading · not confirmed damage
Roofing exposure
What this storm is worth to a roofer.
Potential roof exposure
$360K
Potential roof exposure — 30 homes × the ~$12,000 industry-average hail roof claim. Exposure, not confirmed damage.
Claim window
September 2028
Claims from this storm can typically be filed until around September 2028 — the window to reach these homeowners while it's still open. Deadlines vary by policy and state.
Names and phones for every home in the footprint: at most $6 on top of the $150 plan.
Calvin hail history
Other storms in Calvin.
Estimated-size surface Jul 9, 2026
1.75"
Estimated-size surface Jun 29, 2026
1"
Estimated-size surface Jun 2, 2026
2.5"
Estimated-size surface Jan 2, 2026
1.5"Take your next area into the field.
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