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Gallatin National Forest; Wheatland County/Sweet Grass County; Stillwater County; Beartooth Ranger District Custer National Forest; Golden Valley County/Musselshell County; Yellowstone County
Sweet Grass County, Montana severe weather history spans 188 recorded events between 1955 and 2025. The dominant hazard is hail, accounting for 69.1% of all recorded events. It ranks #2,516 nationally and #36 in Montana.
188
Recorded events
0
Direct deaths
0
Direct injuries
$4.5M
Property damage
The record
What the Sweet Grass County, Montana severe weather history record shows
Across the archive, Sweet Grass County, Montana severe weather history averages 2.7 recorded events a year. The busiest stretch on record is the 2010s, with 90 events logged in that decade alone. Roughly 8 events fall before 1990 and 180 from 1990 onward — a gap that reflects the expansion of NOAA reporting practice as much as the weather itself.
The costliest is flood, with $4.0M in reported property damage. In total, 8 distinct hazard types appear in this county archive, each listed with its own dated record below.
By hazard type
Every hazard type recorded in Sweet Grass County
| Hazard | Events | Deaths | Damage | Max | Span |
|---|---|---|---|---|---|
| Hail | 130 | 0 | $0 | 2.5 | 1955–2025 |
| Thunderstorm Wind | 37 | 0 | $500K | 75 | 1988–2025 |
| Flash Flood | 5 | 0 | $0 | 0 | 1997–2023 |
| Flood | 5 | 0 | $4.0M | 0 | 1997–2022 |
| Heavy Rain | 5 | 0 | $0 | 0 | 1998–2005 |
| Tornado | 2 | 0 | $30 | F1 | 1965–1973 |
| Funnel Cloud | 2 | 0 | $0 | 0 | 2011–2013 |
| Wildfire | 2 | 0 | $0 | 0 | 1998–1998 |
Decade by decade
Sweet Grass County, Montana severe weather history by decade
Reporting practice changed over time — early decades are undercounted, not calmer.
Tornado tracks
Paths crossing this county
2 mapped tornado paths intersect this county: 2 touched down inside it and 0 crossed in from a neighbouring county. This comes from path geometry, not county-tagged reports.
| Date | Scale | Deaths | Injuries | Path length | Origin |
|---|---|---|---|---|---|
| 1965-08-22 | EF1 | 0 | 0 | 1.5 mi | Touched down here |
| 1973-05-20 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Significant flooding occurred on creeks and streams across Sweet Grass County resulting in widespread lowland flooding and numerous county roads flooded, closing roads and resulting in significant damage. Numerous bridges also washed out. Specifically, Upper Deer, Lower Deer, Bridger, Sweet Grass, Big Timber and Otter Creeks Flooded. Specific roads flooded include; Anderson, Lower Sweet Grass, Mendinhaul, and Windsor Loop. At the height of the flooding, water was overtopping Interstate 90 from Mile Post 376 to 377. Damage estimates based on FEMA reviews and Individual Assistance approvals.
County officials and the Montana Department of Transportation reported that small stream and low land flooding occurred across the area. Water was reported to be flowing over Highway 12 near Two Dot and Highway 191 between Harlowton and Judith Gap. Water also flowed across some of the roads along the Beartooth Foothills south of Reed Point and Columbus.
Context
Risk, population and federal disasters
Very Low
FEMA NRI risk rating
3,720
Population (ACS)
$330K
Median home value
10
Federal declarations
| Declared | Incident | Title | Type |
|---|---|---|---|
| Apr 7, 2026 | Straight-Line Winds | SEVERE WINTER STORM AND STRAIGHT-LINE WINDS | DR |
| Jun 16, 2022 | Flood | SEVERE STORM AND FLOODING | DR |
| Mar 31, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Mar 13, 2020 | Biological | COVID-19 | EM |
| Jun 17, 2011 | Severe Storm | SEVERE STORMS AND FLOODING | DR |
| Aug 30, 2006 | Fire | DERBY FIRE | FM |
Quick answers
Frequently asked
How many severe weather events have been recorded in Sweet Grass County, Montana?
188 events are on record between 1955 and 2025, causing 0 direct deaths and $4.5M in property damage.
What is the most common severe weather hazard in Sweet Grass County?
Hail, with 130 recorded events — 69.1% of everything in the archive for this county.
How many tornadoes have crossed Sweet Grass County?
2 mapped tornado paths intersect the county boundary; 2 of them touched down inside it. This is derived from path geometry, not county-tagged reports.
How many federal disaster declarations cover Sweet Grass County?
10 federal disaster declarations from FEMA include Sweet Grass County, each tied to a specific incident period.
How risky is Sweet Grass County compared with the rest of the country?
FEMA's National Risk Index rates Sweet Grass County as very low risk, placing it in the 8 percentile of its state for expected annual loss.
Where does the Sweet Grass County, Montana severe weather history data come from?
Every figure is drawn from United States federal public-domain records: NOAA/NCEI Storm Events for the event archive, NOAA SPC SVRGIS for mapped tornado paths, FEMA for disaster declarations and risk ratings, and the U.S. Census for population context. Dates are shown in UTC and recent entries may still be revised by NOAA.
Nearby
Neighbouring counties
- Stillwater County 287
- Teton County 216
- Silver Bow County 81
- Toole County 143
- Sheridan County 357
- Treasure County 159
Cite this page
“Sweet Grass County, Montana.” Severe Weather History. severeweatherhistory.com/county/montana/sweet-grass-county/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.