Hail in Alton · May 4, 2026
NEXRAD logged 15 hail signatures up to 2.25"; the estimated-size surface reached 1.25" aloft. At 2.25" — tennis ball — this is a severe hail signal associated with roof damage. Open it on the live map to see the swath over the streets.
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Convective day · May 4, 2026 · noon–noon UTC
Severity
The 3rd most severe storm Alton 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
- 56 /100
- Homes exposed
- 78 /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 Alton 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.
Radar signature field NEXRAD radar signatures — the point detections the storm produced overhead. A signature is where the radar saw hail, not a confirmed stone on the ground.
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.
The storm in context
Where May 4, 2026 sits in Alton's hail record.
This was Alton's 4th recorded hail day, arriving 1 day after the May 3, 2026 storm. By severity it ranks 3rd of the 5 storms we have logged here. Radar put the day's largest stone over Alton at 2.25" — the largest NEXRAD radar signature.
The May 4, 2026 convective day was bigger than Alton: the same system put hail over 428 other tracked cities, 239 of them in Illinois. Nearest: Bethalto (5 miles east, up to 2.25"); Hartford (7 miles south, up to 1"); Edwardsville (13 miles southeast, up to 2").
These maps are stills. In the app this date is one of 5 Alton 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.
For this storm over Alton, the NWS report log is empty — a common outcome, since ground reports only happen when someone witnesses the hail and takes the time to call it in. The detection record for the date lives in the radar maps above.
Severe hail signal
What 2.25" hail means for Alton roofs.
Two-inch-plus hail is capable of puncturing shingles, breaking skylights or windows, and heavily denting soft materials. The strongest radar bands warrant prompt inspection, but neither the signal nor the footprint confirms damage at a specific address.
Radar reading · not confirmed damage
Roofing exposure
What this storm is worth to a roofer.
Potential roof exposure
$94M
Potential roof exposure — 7,854 homes × the ~$12,000 industry-average hail roof claim. Exposure, not confirmed damage.
- Illustrative jobs
- 39 jobs
- Illustrative work
- ~$585K
Close just 0.5% of the 7,854 homes in this footprint at the average $15,000 roof job. Illustrative math, not a projection — your results depend on your outreach and how the market responds.
Claim window
May 2028
Claims from this storm can typically be filed until around May 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 $1,649 on top of the $150 plan.
Estimated-size surface Sep 5, 2026
0.5"
Estimated-size surface May 3, 2026
1.75"
Estimated-size surface Apr 27, 2026
2.75"
Estimated-size surface Mar 15, 2026
1"The next storm won’t wait for you.
Set your territory and alerts today. When hail hits, use Overview to choose your streets and get moving.
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