Lyman County was hit as recently as 2026-07-04, 27 days ago. Lyman County is hit in most years, and usually several times over. The largest stone on record here is 4.25 inches and 4.2 times the National Weather Service's 1 inch severe criterion, reported on 2010-07-23 near Vivian.
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 2026-07-04, around Oacoma. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Lyman County addresses inside a hail swath above your size threshold into a door-knock list you can export, scoped to your approved markets.
Get free access Check an addressOur US-based call center calls the homeowners in this storm and books roof inspections straight onto your calendar. You work the storm; we fill the schedule. We dial -- you do not have to knock a single door.
See call-center options ->NOAA's Storm Prediction Center has logged 54 separate hail days here since 2010 -- 3.2 a year over 17 years of record. Those days carry 98 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 2018, with 7 hail days. The last five years track the long-run rate, with 14 days since 2022.
Most hail here stays under 2 inches: only 5 of the 54 days on record passed it, 9%, the last on 2025-07-09. They land in the same month as everything else, July. 22 of the 54 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 Kennebec -- 18 of the county's 54 hail days -- then Presho (12), Oacoma (10), Reliance (9) and Vivian (7). Beyond those, NOAA names Iona, Lower Brule, Lyman, Cedar Creek Rec Are and Joe Creek Rec Are on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Presho | 5 | 3.00″ |
| Kennebec | 4 | 1.75″ |
| Oacoma | 3 | 1.75″ |
| Vivian | 2 | 4.25″ |
| 6 Sse Kennebec | 2 | 3.00″ |
The season runs May through August: 49 of the 54 hail days on record fall in those 4 months (91%). July is the single busiest month, with 15 of them (28%). That peak sits inside the window rather than at either end. Hail has also been reported in September, outside that window. Reports span 5 of the 12 calendar months; the other 7 have never produced one.
| Month | Hail days |
|---|---|
| May | 8 |
| June | 14 |
| July | 15 |
| August | 12 |
| September | 5 |
That day put 1 report on the map, the biggest 1.25 inches near Oacoma. 2 hail days have already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-07-04 | 1.25″ | 1 |
| 2026-06-03 | 1.50″ | 1 |
| 2025-08-13 | 1.00″ | 1 |
| 2025-08-03 | 1.25″ | 2 |
| 2025-07-29 | 1.00″ | 1 |
| 2025-07-28 | 1.75″ | 1 |
| 2025-07-09 | 2.50″ | 1 |
| 2025-06-27 | 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 4.25 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: Brule County (34 hail days), Hughes County (35) and Buffalo County (17). Lyman County takes more hail than any of them.
Brule County · Hughes County · Buffalo 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, Lyman County, South Dakota only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.