The most recent reported hail day was 2026-03-10, 143 days ago. Mercer County is hit in about half the years on record. 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 2023-08-16 near Aledo.
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 2026-03-10, around Seaton. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Mercer 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 13 separate hail days here since 2010 -- 0.8 a year over 17 years of record. They carry 20 reports in total: most hail days here are logged from a single spot. 8 of those 17 years produced none at all. The busiest single year was 2024, with 2 hail days. The last five years have run hotter than the long-run rate: 6 days since 2022, against 0.6 a year before that.
No stone of 2 inches or more has ever been reported in Mercer County: all 13 hail days on record topped out below that. Golf-ball size is rarer still: 1.75 inches or more on 2 of the 13 days.
Across the whole of Illinois, see the Illinois hail map and history.
Reports cluster nearest Aledo -- 3 of the county's 13 hail days -- then Sherrard (3), Millersburg (2) and New Boston (2).
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| 5 Nnw New Boston | 2 | 1.75″ |
| Sherrard | 2 | 1.00″ |
| 4 Nnw Millersburg | 1 | 1.75″ |
| Aledo | 1 | 1.75″ |
| 1 N Gingle Corners | 1 | 1.50″ |
The season runs February through May: 12 of the 13 hail days on record fall in those 4 months (92%). March is the single busiest month, with 4 of them (31%). That peak sits inside the window rather than at either end. Hail has also been reported in August, outside that window. Reports span 5 of the 12 calendar months; the other 7 have never produced one.
| Month | Hail days |
|---|---|
| February | 2 |
| March | 4 |
| April | 3 |
| May | 3 |
| August | 1 |
That day put 1 report on the map, the biggest 1.25 inches near Seaton. 1 hail day has already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-03-10 | 1.25″ | 1 |
| 2025-03-27 | 1.00″ | 1 |
| 2024-04-16 | 1.00″ | 4 |
| 2024-02-27 | 1.25″ | 1 |
| 2023-08-16 | 1.75″ | 2 |
| 2023-04-20 | 1.00″ | 1 |
| 2019-05-25 | 1.25″ | 1 |
| 2017-02-28 | 1.00″ | 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, over the state line included: Rock Island County (24 hail days), Warren County (21), Knox County (25), Scott County, Iowa (31) and Muscatine County, Iowa (21). Every one of them takes more hail than Mercer County.
Rock Island County · Warren County · Knox County · Scott County, Iowa · Muscatine County, Iowa
Back to the Illinois hail map or the U.S. hail map.
Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Mercer County, Illinois only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.