Hail map for Upper Alton, IL — May 4, 2026
NOAA radar detected hail up to 1.00″ — quarter size — within 5 miles of Upper Alton on May 4, 2026.
- Max hail size
- 1.00″
- quarter
- Impact rating
- 3/10
- from stone size
- Size bands over the city
- 1
- distinct radar bands
- Reached the ground
- 30%
- NOAA POSH probability
- Measured on the ground
- 1.50″
- 14.6 mi away · Trained Spotter
NOAA's Probability of Severe Hail peaked at 30% over Upper Alton that day — low to moderate: the radar signature was there, ground impact less certain. It is a separate model from the size estimate above: one asks how big the stones were in the storm, the other asks whether they made it down.
Sizes come from NOAA MRMS radar (MESH), which runs about ±0.25″ against ground truth. It is canvass-targeting quality, not claim evidence.
Work Upper Alton on the live hail map
- The whole state around Upper Alton, with this swath already on it
- Three years of hail swaths, filterable by stone size
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Did hail hit your address?
This page covers Upper Alton as a whole. Check your own address to see every storm on record for your roof — the date and the stone size for each one — and we'll email you the full report to keep.
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Other hail dates for Upper Alton
Every storm over Upper Alton →What people on the ground measured in Upper Alton, IL on May 4, 2026
5 reports filed with the National Weather Service — 2 from trained spotters or officials. These are measured stones, not radar estimates, so they are the closest thing to proof that hail actually reached the ground.
- 1.50″ half dollar size Trained Spotter2 W Worden, IL · 14.6 mi away6:21 PM CDTMadison County
- 1.00″ quarter size Public1 NE Prairietown, IL · 14.3 mi away6:23 PM CDTMadison County
Report from mPING: Quarter (1.00 in.).
- 0.75″ penny size Amateur Radio2 NNE Bethalto, IL · 6.0 mi away6:11 PM CDTMadison County
Lasted about 5 minutes.
- 0.75″ penny size PublicDorsey, IL · 9.1 mi away6:16 PM CDTMadison County
Twitter report.
- 0.70″ penny size Trained Spotter1 SSE Wood River, IL · 5.7 mi away12:37 PM CDTMadison County
Reports come from the National Weather Service Local Storm Report feed, ingested every 15 minutes. A report records where the observer was, not the full extent of the swath — treat it as evidence about the storm, not about any one roof.
Upper Alton hail on May 4, 2026
NOAA radar estimated stones up to 1.00 inches — quarter size — within about 5 miles of Upper Alton that day, across 1 distinct size band. Sizes vary street to street inside a single swath.