The most recent reported hail day was 2025-09-12, 322 days ago. Corson 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 2013-06-21 near Morristown.
Colored swath = NOAA MRMS radar-estimated hail size; dots = NOAA SPC reports in South Dakota. Radar-indicated, not a guarantee of damage.
The last hail here fell on 2025-09-12, around Morristown. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Corson 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 49 separate hail days here since 2010 -- 2.9 a year over 17 years of record. Those days carry 93 separate reports between them, two or three on a typical one. 2 of those 17 years produced none at all. The busiest single year was 2018, with 6 hail days. The last five years have been quieter than the long run: 7 days since 2022, against 3.5 a year before that.
Most hail here stays under 2 inches: only 2 of the 49 days on record passed it, 4%, the last on 2016-08-14. Those big days do not follow the county's usual calendar: most of them fall in June, not July. Golf-ball size is rarer still: 1.75 inches or more on 11 of the 49 days.
Across the whole of South Dakota, see the South Dakota hail map and history.
Reports cluster nearest Keldron -- 8 of the county's 49 hail days -- then Walker (7), Mcintosh (7), Little Eagle (6) and Mclaughlin (6). Beyond those, NOAA names Morristown, Trail City, Watauga, Klein Ranch, Wakpala, Shambo Ranch, Isabel, Bullhead and Mahto on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Morristown | 2 | 2.75″ |
| Mcintosh | 2 | 1.25″ |
| 3 N Trail City | 2 | 1.00″ |
| 7 SSE Mcintosh | 2 | 1.00″ |
| 8 S Keldron | 2 | 1.00″ |
The season runs June through August: 40 of the 49 hail days on record fall in those 3 months (82%). July is the single busiest month, with 17 of them (35%). That peak sits inside the window rather than at either end. Hail has also been reported in May and September, outside that window. Reports span 5 of the 12 calendar months; the other 7 have never produced one.
| Month | Hail days |
|---|---|
| May | 6 |
| June | 11 |
| July | 17 |
| August | 12 |
| September | 3 |
That day put 2 reports on the map, the biggest 1.75 inches near Morristown. No hail day has been reported here yet this year.
| Date | Max hail | Reports |
|---|---|---|
| 2025-09-12 | 1.75″ | 2 |
| 2024-08-28 | 1.00″ | 1 |
| 2024-07-28 | 1.00″ | 1 |
| 2024-06-07 | 1.00″ | 2 |
| 2024-05-19 | 1.25″ | 1 |
| 2023-08-01 | 1.00″ | 1 |
| 2023-07-30 | 1.25″ | 2 |
| 2021-07-08 | 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 2.75 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, over the state line included: Dewey County (51 hail days), Ziebach County (34), Campbell County (28), Sioux County, North Dakota (31) and Grant County, North Dakota (56). Corson County sits in between.
Dewey County · Ziebach County · Campbell County · Sioux County, North Dakota · Grant County, North Dakota
Back to the South Dakota hail map or the U.S. hail map.
Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Corson County, South Dakota only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.