The most recent reported hail day was 2025-08-21, 344 days ago. Grant County is hit in most years. The largest stone on record here is 2.5 inches, a tennis ball and 2.5 times the National Weather Service's 1 inch severe criterion, reported on 2021-08-28 near Milbank.
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 2025-08-21, around Big Stone City. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Grant 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 22 separate hail days here since 2010 -- 1.3 a year over 17 years of record. Those days carry 40 separate reports between them, two or three on a typical one. 4 of those 17 years produced none at all. The busiest single year was 2015, with 3 hail days. The last five years have been quieter than the long run: 3 days since 2022, against 1.6 a year before that.
3 of the 22 days reached 2 inches or more -- 14%, or about one hail day in 7, the last on 2021-08-28. Those big days do not follow the county's usual calendar: most of them fall in August, not June. 7 of the 22 days reached golf-ball size, 1.75 inches or bigger.
Across the whole of South Dakota, see the South Dakota hail map and history.
Reports cluster nearest Milbank -- 7 of the county's 22 hail days -- then Summit (7), Albee (4), Twin Brooks (3) and South Shore (2). Beyond those, NOAA names Big Stone City, Revillo and Strandburg on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Milbank | 3 | 1.75″ |
| 6 S Summit | 2 | 1.75″ |
| Twin Brooks | 2 | 1.75″ |
| 2 N Milbank | 2 | 1.50″ |
| 2 W Milbank | 2 | 1.25″ |
The season runs May through August: 19 of the 22 hail days on record fall in those 4 months (86%). June is the single busiest month, with 6 of them (27%). That peak sits inside the window rather than at either end. Hail has also been reported in September and October, outside that window. Reports span 6 of the 12 calendar months; the other 6 have never produced one.
| Month | Hail days |
|---|---|
| May | 3 |
| June | 6 |
| July | 4 |
| August | 6 |
| September | 1 |
| October | 2 |
That day put 2 reports on the map, the biggest 1 inch near Big Stone City. No hail day has been reported here yet this year.
| Date | Max hail | Reports |
|---|---|---|
| 2025-08-21 | 1.00″ | 2 |
| 2024-06-18 | 1.00″ | 1 |
| 2022-09-08 | 1.00″ | 1 |
| 2021-08-28 | 2.50″ | 4 |
| 2021-08-27 | 2.50″ | 1 |
| 2020-10-11 | 1.00″ | 1 |
| 2020-08-21 | 1.50″ | 3 |
| 2019-06-04 | 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 2.5 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: Codington County (38 hail days), Roberts County (26), Deuel County (22) and Big Stone County, Minnesota (22). Grant County sits in between.
Codington County · Roberts County · Deuel County · Big Stone County, Minnesota
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, Grant County, South Dakota only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.