Dewey County was hit as recently as 2026-06-03, 58 days ago. Dewey County is hit in most years, and usually several times over. The largest stone on record here is 4 inches, a grapefruit and 4 times the National Weather Service's 1 inch severe criterion, reported on 2022-07-05 near Timber Lake.
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 2026-06-03, around Green Grass. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Dewey 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 51 separate hail days here since 2010 -- 3.0 a year over 17 years of record. Those days carry 99 separate reports between them, two or three on a typical one. Exactly one year since 2010 passed with no reported hail day at all. The busiest single year was 2022, with 7 hail days. The last five years track the long-run rate, with 15 days since 2022.
5 of the 51 days reached 2 inches or more -- 10%, or about one hail day in 10, the last on 2022-07-05. Those big days do not follow the county's usual calendar: most of them fall in July, not June. 13 of the 51 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 Timber Lake -- 10 of the county's 51 hail days -- then Firesteel (7), Isabel (6), Ridgeview (6) and Parade (6). Beyond those, NOAA names Lantry, White Horse, Promise, Eagle Butte, Laplant, Glencross, Green Grass, Little Moreau Rec and Mission Ridge on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Timber Lake | 4 | 2.00″ |
| Isabel | 3 | 2.50″ |
| Eagle Butte | 3 | 1.75″ |
| 2 N Timber Lake | 2 | 4.00″ |
| 4 Ne Firesteel | 2 | 2.50″ |
The season runs June through August: 41 of the 51 hail days on record fall in those 3 months (80%). June is the single busiest month, with 17 of them (33%). That peak opens the window: the season starts at its worst and eases off from there. Hail has also been reported in April, May and September, outside that window. Reports span 6 of the 12 calendar months; the other 6 have never produced one.
| Month | Hail days |
|---|---|
| April | 3 |
| May | 4 |
| June | 17 |
| July | 17 |
| August | 7 |
| September | 3 |
That day put 2 reports on the map, the biggest 1 inch near Green Grass. 1 hail day has already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-06-03 | 1.00″ | 2 |
| 2025-07-26 | 1.50″ | 1 |
| 2025-07-14 | 1.00″ | 1 |
| 2025-06-14 | 1.00″ | 1 |
| 2024-06-07 | 1.00″ | 1 |
| 2024-05-19 | 1.00″ | 2 |
| 2023-07-30 | 1.00″ | 1 |
| 2023-06-20 | 1.00″ | 2 |
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 4 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: Ziebach County (34 hail days), Corson County (49) and Walworth County (39). Dewey County takes more hail than any of them.
Ziebach County · Corson County · Walworth County
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, Dewey County, South Dakota only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.