States › Montana › Jefferson County
Jefferson County, Montana
Recorded hazard history: storm events since 1950, federal disaster declarations since 1953, flood insurance claims since 1978, and FEMA's risk index.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. NCEI storm records through 30 Jun 2026; OpenFEMA declarations refreshed 1 Oct 2026; NFIP claims as of 8 Sep 2026.
The NCEI record lists 248 events for Jefferson County, Montana, between 1950 and 2026; winter storms and snow account for the largest share.
That is 15.0 events per 100 square miles, below the Montana figure of 24.9, and 198.9 per 10,000 residents against 328.5 statewide.
4 events fall in the 12 months to 30 Jun 2026. NCEI attributes 0 deaths and 2 injuries to events in the county, with property damage estimated at $300K.
FEMA has designated the county in 11 federal disaster declarations since 1953; the most recent is Covid-19 Pandemic (major disaster, 31 Mar 2020).
National Flood Insurance Program policyholders in the county filed 5 claims since 1978, of which 4 were paid, totalling $7K (about $2K per paid claim). FEMA counts 22 residential flood policies in force.
FEMA's National Risk Index rates the county's overall risk as "Very Low" and its expected annual loss as "Very Low" ($8.6M a year across 18 hazards).
Compared with Montana and the United States
| Measure | Jefferson County | Montana | US |
|---|---|---|---|
| Recorded events since 1950 | 248 | 36,277 | 1,977,440 |
| Events per 100 square miles | 15.0 | 24.9 | 56.0 |
| Events per 10,000 residents | 198.9 | 328.5 | 59.6 |
| Events in the last 12 months | 4 | 1,522 | 62,008 |
| Deaths recorded by NCEI | 0 | 166 | 26,435 |
| Property damage (NCEI estimates) | $300K | $369M | $575B |
| NFIP claims per 1,000 residents | 0.4 | 2.0 | 8.1 |
| Average paid NFIP claim | $2K | $12K | $43K |
| Claims per 100 policies in force, last 10 years | 0.0 | 9.8 | 16.1 |
County-recorded events plus zone-recorded events whose forecast zone is named for the county. State and US rows include events recorded only by forecast zone. Rates use 2021 Census population and land area.
Events by decade
Trend: 187 events in the 20 years to 2025 against 45 in the 20 years before. Reporting practice changed in 1996 and again with automated reports in the 2000s, so decade totals measure the record as much as the weather.
Events by type
Hazard pages exist for hail, tornado, flood, wind and winter where the county has at least 10 recorded events. "Other" covers heavy rain, debris flow, dust, funnel clouds and similar reports.
Largest recorded events
| Date | Event type | Group | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|---|
| 2 Aug 2000 | Wildfire | Wildfire | — | — | — | — | 2 | County |
| 2 Jul 1998 | Flash Flood | Flood | — | $100K | — | — | — | County |
| 27 Jun 2023 | Flash Flood | Flood | — | $100K | — | — | — | County |
Ranked by deaths, then injuries, then NCEI's damage estimate. Deaths and injuries are NCEI counts (direct plus indirect); no personal details are recorded here.
Federal disaster declarations
| Declared | Number | Type | Incident | Title | Programs |
|---|---|---|---|---|---|
| 31 Mar 2020 | DR-4508 | Major disaster | Biological | Covid-19 Pandemic | Individual assistance, Public assistance |
| 13 Mar 2020 | EM-3476 | Emergency | Biological | Covid-19 | Public assistance |
| 17 Apr 2014 | DR-4172 | Major disaster | Flood | Ice Jams And Flooding | Public assistance |
| 29 Aug 2012 | FM-5008 | Fire management assistance | Fire | Nineteen Mile Fire | Public assistance |
| 17 Jun 2011 | DR-1996 | Major disaster | Severe Storm | Severe Storms And Flooding | Individual assistance, Public assistance |
| 13 Sep 2005 | EM-3253 | Emergency | Hurricane | Hurricane Katrina Evacuation | Public assistance |
| 30 Aug 2000 | DR-1340 | Major disaster | Fire | Wildfires | Individual assistance |
| 24 Jul 2000 | FM-2314 | Fire management assistance | Fire | Mt - Central Zone 3b Fire Complex | Public assistance |
| 23 Feb 1996 | DR-1105 | Major disaster | Severe Storm | Severe Storms, Flooding, And Ice Jams | Public assistance |
| 27 May 1981 | DR-640 | Major disaster | Flood | Severe Storms & Flooding | Individual assistance, Public assistance |
| 28 Jun 1975 | DR-472 | Major disaster | Flood | Rains, Showmelt, Storms & Flooding | Individual assistance, Public assistance |
Declarations in which FEMA designated this county, from the OpenFEMA Disaster Declarations Summaries (v2). DR: major disaster; EM: emergency; FM: fire management assistance. Programs show whether individual or public assistance was made available.
Flood insurance claims
| Year of loss | Claims | Paid claims | Amount paid | Average paid |
|---|---|---|---|---|
| 2011 | 4 | 3 | $5,729 | $1,910 |
| 2008 | 1 | 1 | $1,236 | $1,236 |
OpenFEMA NFIP claims (v3, as of 8 Sep 2026), aggregated by year of loss; amounts are building, contents and increased-cost-of-compliance payments as recorded. Repetitive-loss counts from the NFIP Multiple Loss Properties file (2 Aug 2026); policies in force from the NFIP Residential Penetration Rates file (3 Aug 2026).
National Risk Index
| Hazard (NRI) | Risk rating | Expected annual loss |
|---|---|---|
| Inland flooding | $3,850,467 | |
| Cold wave | $1,760,629 | |
| Wildfire | $1,328,569 | |
| Earthquake | $672,340 | |
| Lightning | $358,438 | |
| Winter weather | $213,295 | |
| Landslide | $184,525 | |
| Hail | $78,128 | |
| Strong wind | $56,177 | |
| Tornado | $27,450 | |
| Heat wave | $20,808 | |
| Drought | $4,300 | |
| Ice storm | $3,809 | |
| Avalanche | $23 |
FEMA National Risk Index, December 2025 release. Ratings are FEMA's relative comparison of counties; expected annual loss is FEMA's modelled estimate of average yearly building, population and agriculture loss. See how to read the NRI.
Hurricane and tropical storm passes
No HURDAT2 track at tropical-storm strength passes within 100 miles of the county's centre point (through the 2025 season).
Questions and answers
How often does it hail in Jefferson County, MT?
NCEI records 56 hail events in Jefferson County since 1950, in 24 different years; that is about 0.7 recorded events a year. 4 reports were golf-ball size (1.75 in) or larger.
Has Jefferson County had a tornado?
Yes. NCEI records 1 tornado in Jefferson County since 1950, 0 of them rated (E)F2 or stronger. Tornado deaths recorded: 0.
When was the last federal disaster declaration for Jefferson County?
31 Mar 2020: Covid-19 Pandemic, a major disaster declaration for biological. The county appears in 11 declarations since 1953.
How many flood insurance claims have been filed in Jefferson County, and how much was paid?
5 NFIP claims since 1978, 4 of them paid, for $7K in total. FEMA publishes these figures redacted and aggregated; individual properties are not identified.
Is Jefferson County in the National Risk Index's high-risk band?
FEMA's National Risk Index (December 2025) rates the county "Very Low" for overall risk, "Very Low" for expected annual loss, "Relatively Low" for social vulnerability and "Relatively Low" for community resilience. These ratings are FEMA's relative comparison across all US counties.
How does Jefferson County compare with the rest of Montana?
15.0 recorded events per 100 square miles against 24.9 statewide, and 0.4 NFIP claims per 1,000 residents against 2.0. The comparison table on this page shows each measure beside the state and national figures.
Provenance
Storm events: NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026 (public domain). Declarations: OpenFEMA DisasterDeclarationsSummaries v2, refreshed 1 Oct 2026. Flood claims: OpenFEMA NfipClaims v3 as of 8 Sep 2026; NfipMultipleLossProperties v1 (2 Aug 2026); NfipResidentialPenetrationRates v1 (3 Aug 2026). Risk index: FEMA National Risk Index, December 2025. Hurricane tracks: NHC HURDAT2 through 2025. Population and area: US Census Bureau, 2021 vintage. Built 1 Oct 2026; see the methodology and corrections pages. Hazard hubs: Hail · Tornado · Flood · Wind · Winter.