The most recent reported hail day was 2026-04-17, 105 days ago. Knox County is hit in most years. The largest stone on record here is 1.75 inches, a golf ball and 1.8 times the National Weather Service's 1 inch severe criterion, reported on 2026-04-17 near Williamsfield.
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 2026-04-17, around Williamsfield. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Knox County addresses inside a hail swath above your size threshold into a door-knock list you can export, scoped to your approved markets.
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See call-center options ->NOAA's Storm Prediction Center has logged 25 separate hail days here since 2010 -- 1.5 a year over 17 years of record. They carry 34 reports in total: most hail days here are logged from a single spot. 5 of those 17 years produced none at all. The busiest single year was 2017, with 4 hail days. The last five years have been quieter than the long run: 4 days since 2022, against 1.8 a year before that.
No stone of 2 inches or more has ever been reported in Knox County: all 25 hail days on record topped out below that. 7 of the 25 days reached golf-ball size, 1.75 inches or bigger.
Across the whole of Illinois, see the Illinois hail map and history.
Reports cluster nearest Galesburg -- 7 of the county's 25 hail days -- then Abingdon (4), Knoxville (4), Altona (3) and Rio (3). Beyond those, NOAA names Henderson on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Altona | 3 | 1.75″ |
| Galesburg | 3 | 1.75″ |
| Rio | 3 | 1.75″ |
| Abingdon | 2 | 1.75″ |
| 1 N Galesburg | 2 | 1.00″ |
The season runs February through June: 20 of the 25 hail days on record fall in those 5 months (80%). May is the single busiest month, with 7 of them (28%). That peak sits inside the window rather than at either end. Hail has also been reported in August, September and November, outside that window. Reports span 8 of the 12 calendar months; the other 4 have never produced one.
| Month | Hail days |
|---|---|
| February | 1 |
| March | 4 |
| April | 5 |
| May | 7 |
| June | 3 |
| August | 1 |
| September | 2 |
| November | 2 |
That day put 2 reports on the map, the biggest 1.75 inches near Williamsfield. 1 hail day has already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-04-17 | 1.75″ | 2 |
| 2024-06-25 | 1.75″ | 1 |
| 2024-05-02 | 1.00″ | 1 |
| 2023-03-31 | 1.00″ | 1 |
| 2020-11-10 | 1.00″ | 1 |
| 2020-04-08 | 1.00″ | 1 |
| 2020-04-07 | 1.50″ | 1 |
| 2019-09-27 | 1.75″ | 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 1.75 inches, which is the red band. Look up a street address with the hail history by address tool.
The nearest counties with a page of their own: Warren County (21 hail days), Henry County (37) and Mercer County (13). Knox County sits in between.
Warren County · Henry County · Mercer 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, Knox County, Illinois only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.