Sioux County was hit as recently as 2026-06-27, 34 days ago. Sioux County is hit in most years, often more than once. 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 2022-08-18 near Rock Valley.
Colored swath = NOAA MRMS radar-estimated hail size; dots = NOAA SPC reports in Iowa. Radar-indicated, not a guarantee of damage.
The last hail here fell on 2026-06-27, around Hull. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Sioux 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 39 separate hail days here since 2010 -- 2.3 a year over 17 years of record. Those days carry 72 separate reports between them, two or three on a typical one. 3 of those 17 years produced none at all. The busiest single year was 2014, with 5 hail days. The last five years track the long-run rate, with 10 days since 2022.
Most hail here stays under 2 inches: only 2 of the 39 days on record passed it, 5%, the last on 2022-08-18. Those big days do not follow the county's usual calendar: most of them fall in July, not June. Golf-ball size is rarer still: 1.75 inches or more on 7 of the 39 days.
Across the whole of Iowa, see the Iowa hail map and history.
Reports cluster nearest Hawarden -- 12 of the county's 39 hail days -- then Rock Valley (9), Hull (5), Sioux Center (5) and Boyden (5). Beyond those, NOAA names Alton, Ireton, Hudson, Matlock, Granville, Orange City and Chatsworth on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Hawarden | 7 | 1.25″ |
| Rock Valley | 5 | 1.25″ |
| Boyden | 4 | 1.50″ |
| Sioux Center | 3 | 1.75″ |
| 1 W Granville | 2 | 2.00″ |
The season runs May through August: 33 of the 39 hail days on record fall in those 4 months (85%). June is the single busiest month, with 10 of them (26%). That peak sits inside the window rather than at either end. Hail has also been reported in April and September, outside that window. Reports span 6 of the 12 calendar months; the other 6 have never produced one.
| Month | Hail days |
|---|---|
| April | 2 |
| May | 8 |
| June | 10 |
| July | 7 |
| August | 8 |
| September | 4 |
That day put 1 report on the map, the biggest 1 inch near Hull. 2 hail days have already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-06-27 | 1.00″ | 1 |
| 2026-05-18 | 1.00″ | 1 |
| 2025-09-21 | 1.75″ | 1 |
| 2025-06-14 | 1.00″ | 1 |
| 2025-06-02 | 1.75″ | 3 |
| 2024-06-02 | 1.25″ | 1 |
| 2023-07-10 | 1.50″ | 2 |
| 2023-07-03 | 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: Lyon County (30 hail days), Plymouth County (40) and O'Brien County (34). Sioux County sits in between.
Lyon County · Plymouth County · O'Brien County
Back to the Iowa hail map or the U.S. hail map.
Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Sioux County, Iowa only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.