Jefferson County was hit as recently as 2026-07-16, 15 days ago. Jefferson County is hit in most years. The largest stone on record here is 1.5 inches, a ping-pong ball and 1.5 times the National Weather Service's 1 inch severe criterion, reported on 2019-08-10 near Boulder.
Colored swath = NOAA MRMS radar-estimated hail size; dots = NOAA SPC reports in Montana. Radar-indicated, not a guarantee of damage.
The last hail here fell on 2026-07-16, around Clancy. A free SwathIQ account -- hand-reviewed, invite within 24-48h -- pulls Jefferson 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 18 separate hail days here since 2010 -- 1.1 a year over 17 years of record. They carry 32 reports in total: most hail days here are logged from a single spot. 6 of those 17 years produced none at all. One year dominates the record: 2019 alone produced 4 of the 18 days. The last five years track the long-run rate, with 4 days since 2022.
No stone of 2 inches or more has ever been reported in Jefferson County: all 18 hail days on record topped out below that.
Across the whole of Montana, see the Montana hail map and history.
Reports cluster nearest Whitehall -- 5 of the county's 18 hail days -- then Basin (4), Montana City (4), Boulder (3) and Cardwell (3). Beyond those, NOAA names Clancy and Silver Star on more than one hail day apiece.
| Place | Hail days since 2010 | Largest stone |
|---|---|---|
| Whitehall | 4 | 1.50″ |
| Basin | 3 | 1.50″ |
| 2 Se Montana City | 2 | 1.00″ |
| Clancy | 2 | 1.00″ |
| 15 N Cardwell | 1 | 1.50″ |
The season runs June through August: 16 of the 18 hail days on record fall in those 3 months (89%). July is the single busiest month, with 10 of them (56%). 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 | 1 |
| June | 3 |
| July | 10 |
| August | 3 |
| September | 1 |
That day put 2 reports on the map, the biggest 1 inch near Clancy. 1 hail day has already been reported this year.
| Date | Max hail | Reports |
|---|---|---|
| 2026-07-16 | 1.00″ | 2 |
| 2025-07-28 | 1.00″ | 1 |
| 2023-07-06 | 1.00″ | 1 |
| 2022-07-24 | 1.00″ | 1 |
| 2019-08-10 | 1.50″ | 6 |
| 2019-07-16 | 1.00″ | 4 |
| 2019-07-12 | 1.50″ | 1 |
| 2019-06-27 | 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 1.5 inches, which is the red band. Look up a street address with the hail history by address tool.
The nearest counties with a page of their own: Lewis and Clark County (22 hail days), Powell County (14) and Gallatin County (19). Jefferson County sits in between.
Lewis and Clark County · Powell County · Gallatin County
Back to the Montana hail map or the U.S. hail map.
Data & method: NOAA/NWS Storm Prediction Center reports + NOAA MRMS MESH radar, Jefferson County, Montana only. Radar-indicated and observation-based -- informational only, not a guarantee of damage or a valid claim.