Montana has recorded 8,089 hail events from 1955 to 2024, placing the state in the top 20 nationally (rank #17 of 50). The largest hailstone documented in Montana measured 6 inches — softball-sized. Since 1996, the National Weather Service has logged approximately $4.4M in property and crop damage from Montana hail, with the heaviest activity concentrated in July (3,116 events, the state’s busiest hail month) and the most active period (events per year) being 2000-09.
The interactive map below plots every recorded Montana hail report from the NOAA Storm Prediction Center archive. Use the Min Size buttons to focus on damaging hail (1.75″ golf-ball and larger), or filter by Era to see how activity has shifted over the decades.
Interactive Montana Hail Storm Map
Montana hail by the numbers
| Metric | Montana value |
|---|---|
| Total recorded hail events (1955-2024) | 8,089 |
| National rank (event volume) | #17 of 50 states |
| Largest hailstone on record | 6″ (softball-sized) |
| Busiest month | July (3,116 events) |
| Most active period (events/year) | 2000-09 |
| Total recorded damage (1996+) | $4.4M |
| Hail-related injuries (1996+) | 5 |
10 largest hailstones ever recorded in Montana
These are the top ten hail reports in Montana ranked by hailstone diameter. Sizes are NOAA’s measured-or-estimated diameter at time of report.
| Date | Hail size | Comparison | Reported damage | Casualties |
|---|---|---|---|---|
| 1965-07-11 | 6″ | softball-sized | — | — |
| 1971-06-03 | 6″ | softball-sized | — | — |
| 1991-08-13 | 4.5″ | softball-sized | — | — |
| 1999-07-21 | 4.5″ | softball-sized | — | — |
| 2001-07-20 | 4.5″ | softball-sized | — | — |
| 1999-07-18 | 4.5″ | softball-sized | — | — |
| 1969-07-03 | 4.5″ | softball-sized | — | — |
| 1995-08-26 | 4.5″ | softball-sized | — | — |
| 1996-06-26 | 4.5″ | softball-sized | — | — |
| 1996-06-26 | 4.5″ | softball-sized | — | — |
Costliest Montana hailstorms since 1996
Property loss totals come from the National Weather Service’s Storm Events Database. Pre-1996 figures are excluded because the dataset used categorical loss codes rather than dollar amounts before that year.
| Date | Hail size | Property + crop loss | Casualties |
|---|---|---|---|
| 2022-07-07 | 2.5″ | $1.5M | — |
| 2016-07-10 | 2″ | $1.0M | — |
| 2023-07-30 | 2″ | $1.0M | — |
| 2016-06-09 | 2″ | $500K | — |
Hail size distribution in Montana
How Montana’s 8,089 hail events break down by hailstone size. Hail under 1″ is treated as marginally severe; the National Weather Service issues severe-thunderstorm warnings starting at 1″ (quarter size).
| Hailstone size | Events | Share of Montana total |
|---|---|---|
| Under 1″ (pea to dime) | 2,657 | 32.8% |
| 1.00-1.74″ (quarter) | 3,597 | 44.5% |
| 1.75-1.99″ (golf ball) | 1,240 | 15.3% |
| 2.00-2.74″ (egg / hen-egg) | 377 | 4.7% |
| 2.75-3.99″ (baseball) | 183 | 2.3% |
| 4.00″+ (softball or larger) | 35 | 0.4% |
Activity by decade
Recorded hail events have risen across most US states over the decades — partly because of more severe weather, but largely because of vastly improved spotter networks, mobile reporting, and dual-polarisation radar coverage that came online widely after 2010. The events-per-year column normalises the 45-year pre-2000 bucket against the modern 10-year and 5-year periods so the trend is comparable.
| Period | Total events | Events per year |
|---|---|---|
| Pre-2000 (1955-99) | 1,797 | 40 |
| 2000-09 | 3,063 | 306 |
| 2010-19 | 2,515 | 252 |
| 2020-24 | 714 | 143 |
When Montana’s hail season peaks
Montana’s hail activity by calendar month, summed across all years from 1955 to 2024.
| Month | Events |
|---|---|
| January | 0 |
| February | 0 |
| March | 8 |
| April | 37 |
| May | 755 |
| June | 2,745 |
| July | 3,116 |
| August | 1,242 |
| September | 182 |
| October | 4 |
| November | 0 |
| December | 0 |
Where Montana fits in the US hail picture
Montana sits on the eastern or southern edge of Hail Alley — the corridor running from the Texas Panhandle through Oklahoma, Kansas, Nebraska, eastern Colorado and the Dakotas. Hail in Montana tends to be driven less by classic Plains supercells and more by squall lines, mesoscale convective complexes, and warm-season cold-front passages. That means hail events here are common but the truly giant stones (3″+) are rarer than in the core Alley states.
Compare Montana’s hail risk with its neighbours: Idaho hail, Wyoming hail, South Dakota hail, North Dakota hail.
Frequently asked questions about Montana hailstorms
What is the largest hailstone ever recorded in Montana?
According to NOAA Storm Prediction Center data, the largest measured hailstone in Montana was 6 inches in diameter — softball-sized. The map above plots that event along with every other hail report on file for the state.
When does Montana get the most hail?
July is Montana’s busiest hail month, with 3,116 recorded events — the highest single-month total in the state’s NOAA record. Most Montana hail falls in the spring and early-summer convective season; you can see the full month-by-month breakdown in the seasonality table above.
Where in Montana does hail occur most often?
Use the interactive map above to identify the highest-density hail corridors. Pan, zoom and click any point to see the date, size and reported damage for that event. Patterns vary across Montana — in many states the heaviest activity clusters along specific corridors driven by local terrain, lake effects, or jet-stream positioning.
Is Montana’s hail activity getting worse?
Roughly steady or modestly declining in the recent record — but interpret the trend with care. The recorded count has risen across nearly every state because spotter networks, mobile reporting apps, and dual-polarisation radar all expanded dramatically after about 2010. So a rising count partly reflects better detection rather than purely worse weather. The size-distribution and damage tables above are slightly less affected by this reporting bias.
How is hail size measured?
Reports use estimated maximum hailstone diameter in inches, usually compared to common objects: 0.75″ (penny), 1″ (quarter, the severe threshold), 1.75″ (golf ball), 2″ (egg), 2.75″ (baseball), 4″ (softball). The largest verified US hailstone, recorded in Vivian, South Dakota in 2010, measured 8 inches across.
Data sources and limitations
All hail event data on this page comes from the NOAA Storm Prediction Center SVRGIS dataset, accessed via an Esri feature service. The dataset contains over 400,000 individual US hail reports from 1955 to 2024. Property and crop loss values are recorded in actual dollar amounts from 1996 onward (categorical codes were used pre-1996, so loss totals on this page exclude those earlier years). Hailstone sizes are reported as measured-or-estimated maximum diameters; report density is influenced by population, road networks, and the modernisation of spotter networks over time.
Related Mapscaping resources: US Hailstorms map (national hub) · NOAA Storm Reports map (tornadoes, hail and wind)
