The most recent reported hail day was 2024-05-07 -- 2 years ago, with nothing reported since. Grundy County is hit in about half the years on record. The largest stone on record here is 4.25 inches and 4.2 times the National Weather Service's 1 inch severe criterion, reported on 2015-06-10 near Minooka.
Colored swath = NOAA MRMS radar-estimated hail size; dots = NOAA SPC reports in Illinois. Radar-indicated, not a guarantee of damage.
The last hail here fell on 2024-05-07, around Channahon. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Grundy County addresses inside a hail swath above your size threshold into a door-knock list you can export, scoped to your approved markets.
Get free access Check an addressOur US-based call center calls the homeowners in this storm and books roof inspections straight onto your calendar. You work the storm; we fill the schedule. We dial -- you do not have to knock a single door.
See call-center options ->NOAA's Storm Prediction Center has logged 14 separate hail days here since 2010 -- 0.8 a year over 17 years of record. They carry 25 reports in total: most hail days here are logged from a single spot. 8 of those 17 years produced none at all. One year dominates the record: 2015 alone produced 3 of the 14 days. The last five years have been quieter than the long run: 2 days since 2022, against 1.0 a year before that.
Most hail here stays under 2 inches: only 1 of the 14 days on record passed it, 7%, the last on 2015-06-10. Those big days do not follow the county's usual calendar: most of them fall in June, not April. Golf-ball size is rarer still: 1.75 inches or more on 3 of the 14 days.
Across the whole of Illinois, see the Illinois hail map and history.
Reports cluster nearest Morris -- 5 of the county's 14 hail days -- then Minooka (3) and Mazon (3).
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Morris | 4 | 1.50″ |
| Minooka | 2 | 4.25″ |
| Mazon | 2 | 1.00″ |
| 2 Nnw Morris | 1 | 1.75″ |
| 1 Sw Minooka | 1 | 1.25″ |
The season runs April through August: 12 of the 14 hail days on record fall in those 5 months (86%). April is the single busiest month, with 3 of them (21%). That peak opens the window: the season starts at its worst and eases off from there. Hail has also been reported in March and November, outside that window. Reports span 7 of the 12 calendar months; the other 5 have never produced one.
| Month | Hail days |
|---|---|
| March | 1 |
| April | 3 |
| May | 3 |
| June | 3 |
| July | 1 |
| August | 2 |
| November | 1 |
That day put 1 report on the map, the biggest 1 inch near Channahon. No hail day has been reported here yet this year.
| Date | Max hail | Reports |
|---|---|---|
| 2024-05-07 | 1.00″ | 1 |
| 2022-04-30 | 1.00″ | 1 |
| 2020-08-10 | 1.75″ | 2 |
| 2019-03-14 | 1.00″ | 1 |
| 2015-06-10 | 4.25″ | 4 |
| 2015-06-07 | 1.00″ | 1 |
| 2015-04-08 | 1.25″ | 1 |
| 2014-08-26 | 1.25″ | 1 |
The colored swath is NOAA's MRMS radar estimate of the largest hail per ~1 km cell; the dots are SPC ground reports. Yellow is about an inch, red 1.5 to 2″, purple 2″ and up (hail size vs roof damage). On this county's worst day the reports reached 4.25 inches, which is the purple band. Look up a street address with the hail history by address tool.
The nearest counties with a page of their own: Kendall County (16 hail days), Will County (56) and Kankakee County (29). Every one of them takes more hail than Grundy County.
Kendall County · Will County · Kankakee County
Back to the Illinois hail map or the U.S. hail map.
Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Grundy County, Illinois only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.