Cook County, Illinois Hail Map & History
Cook County was hit as recently as 2026-07-27, 49 days ago. Cook County is hit in most years, and usually several times over. The largest stone on record here is 2.75 inches, a baseball and 2.8 times the National Weather Service's 1 inch severe criterion, reported on 2020-04-07 near Evanston.
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 2026-07-27, around Willowbrook. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Cook 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 ->How often it hails in Cook County
NOAA's Storm Prediction Center has logged 76 separate hail days here since 2010 -- 4.5 a year over 17 years of record. Those days carry 333 separate reports between them, better than three on a typical one. No year since 2010 has gone by without at least one. The busiest single year was 2024, with 8 hail days. The last five years track the long-run rate, with 22 days since 2022.
13 of the 76 days reached 2 inches or more -- 17%, or about one hail day in 6, the last on 2026-03-30. Those big days do not follow the county's usual calendar: most of them fall in April, not June. 22 of the 76 days reached golf-ball size, 1.75 inches or bigger.
Across the whole of Illinois, see the Illinois hail map and history.
Hardest-hit places in Cook County
Reports cluster nearest Chicago -- 10 of the county's 76 hail days -- then Hoffman Estates (8), Palatine (7), Oak Lawn (7) and Schaumburg (7). Beyond those, NOAA names Evanston, Lemont, Evergreen Park, Franklin Park, Arlington Heights, Orland Park, Mount Prospect, La Grange Park and Oak Forest on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Chicago | 7 | 2.00″ |
| Hoffman Estates | 6 | 1.25″ |
| Park Ridge | 4 | 1.75″ |
| 1 E Palatine | 4 | 1.50″ |
| Orland Park | 4 | 1.50″ |
When it hails in Cook County
The season runs March through August: 65 of the 76 hail days on record fall in those 6 months (86%). June is the single busiest month, with 16 of them (21%). That peak sits inside the window rather than at either end. December are the only months that have never produced a reported hail day.
| Month | Hail days |
|---|---|
| January | 1 |
| February | 4 |
| March | 7 |
| April | 9 |
| May | 14 |
| June | 16 |
| July | 9 |
| August | 10 |
| September | 3 |
| October | 2 |
| November | 1 |
Recent Cook County hail days
That day put 19 reports on the map, the biggest 1.75 inches near Willowbrook. 5 hail days have already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-07-27 | 1.75″ | 19 |
| 2026-04-14 | 1.00″ | 2 |
| 2026-03-30 | 2.00″ | 9 |
| 2026-03-26 | 1.00″ | 3 |
| 2026-03-10 | 2.00″ | 13 |
| 2025-09-21 | 1.25″ | 1 |
| 2025-08-16 | 1.25″ | 6 |
| 2025-05-15 | 1.25″ | 3 |
How to read the Cook County map
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 2.75 inches, which is the purple band. Look up a street address with the hail history by address tool.
Nearby counties
The nearest counties with a page of their own: DuPage County (35 hail days), Will County (57) and Kane County (44). Cook County takes more hail than any of them.
DuPage County · Will County · Kane County
Back to the Illinois hail map or the U.S. hail map.
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Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Cook County, Illinois only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.