Montana Hazards

On November 1, 2013, the Federal Emergency Management Agency (FEMA) approved the State of Montana Multi-Hazard Mitigation Plan and Statewide Hazard Assessment.  The plan was developed to document historical hazard events and vulnerabilities and strategies for mitigation that will make Montana a more disaster resilient state.

The plan documents hazards in Montana, which are listed (by rank) below. A full version of the document can be accessed by clicking here.

It is important that all Montanans are prepared for disasters and emergencies of all types. Click here to learn more about how you can prepare yourself, your family, and your community.


wildfireWildland and rangeland fire is the #1 natural hazard in Montana according to the 2013 update to the State of Montana Pre-Disaster Mitigation and Statewide Hazard

Assessment. Wildland and rangeland fires impact Montana every year. In mild fire seasons, there may be relatively small timber and crop resource losses. In extreme years, there can be resource devastation, habitat destruction, structure losses and deaths. Historically, fire has been an integral part of forest and grassland regeneration. Fire plays an important role in the growth and generation of healthy forest and grassland habitats.

According to the State of Montana Department of Natural Resources and Conservation (DNRC) from 1981 to 2013, approximately 47 percent of wildfires were started by lightning and 53 percent were human-caused. The primary sources of human caused fires included debris burns, campfires, equipment-caused fires, and railroad starts.

wildland or rangeland fire is an uncontrolled fire, a term which includes grass fires, forest fires, and scrub fires, be they man caused or natural in origin. The wildland/urban interface (WUI) is defined as the zone where structures and other human development meet or intermingle with undeveloped wildland or vegetative fuel.

It Happened in Montana

The 2012 fire season was the most devastating season on record since 1910 in the state of Montana. Approximately 1.1 million acres burned across the state with the suppression efforts costing over $113 million. In June 2012, the Ash Creek fire exploded in Rosebud and Powder River counties. The fire burned 249,562 acres, making this the largest fire of the year. The fire burned 39 structures, including homes on the Northern Cheyenne Indian Reservation and cost $7.5 million to suppress.


Firewise Communities
National Interagency Fire Center
Montana DNRC Fire and Aviation Information
FireSafe Montana
Keep Montana Green
Inciweb: Montana

Glasgow Flooding

Flooding in Glasgow, MT/ David Ewer

Floods are the result of a multitude of naturally-occurring and human-induced factors, but they all can be defined as the accumulation of too much water in too little time in a specific area. The types of floods that affect Montana include:  riverine floods, flash floods, ice jams, and dam failures.

Riverine floods: Riverine floods result from precipitation over large areas and/or from snowmelt. This type of flood occurs in river systems whose tributaries may drain large geographic areas and include many independent river basins. The duration of riverine floods may vary from a few hours to many days.

Flash floods: Flash floods are local floods of great volume and short duration. In contrast to riverine flooding, this type of flood usually results from a torrential rain on a relatively small drainage area. The flood wave from flash floods can move downstream too fast to allow escape. Most flood-related deaths are due to flash floods. Fifty percent of all flash flood fatalities are vehicle related. Two feet of water is all that is necessary to carry most vehicles downstream during a flood.

Ice Jam: An ice jam is an accumulation of ice in a river that restricts water flow and may cause backwater that floods low-lying areas upstream from the jam. Downstream areas also can be flooded if the jam releases suddenly, sending a flash flood downstream. Damages resulting from ice jams can affect roads, bridges, buildings, and homes, and can cost the affected community thousands to millions of dollars. Montana has the most ice jams in the continental United States with 2/3 of the jams occurring in February and March.

Dam Failure Floods: Dam failure floods are usually associated with intense rainfall or prolonged flood conditions, but can occur during an earthquake. Dam failure may be caused by faulty design, construction and operational inadequacies, intentional breaches, or a flood event larger than the design flood. The greatest threat from dam failure is to people and property in areas immediately below the dam since flood discharges decrease as the flood wave moves downstream.

It Happened in Montana

A Major Disaster Declaration was declared by President Obama on June 17, 2011 for the State of Montana. Flooding resulting from heavy rains and snow melt from record snow occurred throughout the state. 46 out of 56 states were affected along with 6 of the 7 Tribal Nations. Damages were estimated at over $60 million statewide.


National Flood Insurance Program
Community Rating System Program
Montana DNRC Floodplain Management
Flood Preparedness: FEMA


An earthquake is the ground shaking and radiated seismic energy caused most commonly by a sudden slip on a fault, volcanic or magmatic activity, or other sudden stress changes in the earth.

A belt of seismicity known as the Intermountain Seismic Belt extends through western Montana, from the Flathead Lake region in the northwest corner of the state to the Yellowstone National Park area, making Montana one of the most seismically active states.

It Happened in Montana

hebgen lakeThe Hebgen Lake magnitude 7.5 earthquake, which occurred on August 18, 1959, was the largest earthquake in Montana and the 14th largest earthquake in the contiguous U.S. in historic times (Stover and Coffman, 1993). The earthquake caused 29 fatalities and about $11million in damage to highways and timber. The most spectacular and disastrous effect of the earthquake was the huge landslide of rock, soil, and trees that cascaded from the steep south wall of Madison River Canyon, creating the 174 foot deep Quake Lake.


Great Montana ShakeOut
Montana Bureau of Mines and Geology Earthquake Studies
Personalizing the Earthquake Threat
U.S. Geological Survey Earthquake Information: Montana

Severe Summer Weather

Severe summer weather includes thunderstorms, wind, hail, lightening, tornadoes and microbursts that typically occur between May and October each year.

Thunderstorm: A thunderstorm is formed from a combination of moisture, rapidly rising warm air, and a force of capable lifting air, such as a warm and cold front or a mountain. A severe thunderstorm is a thunderstorm that produces tornadoes, hail of 1 inch or more in diameter, or winds of 58 mph or more.

High Winds: High Winds can affect the entire state with wind speeds in excess of 75-100 mph. A Chinook is a warm wind that develops down the east slopes of the Rocky Mountains. At times, these winds can reach several hundreds of miles into the high plains.

Lightning: Lightning is an electrical discharge that results from the buildup of positive and negative charges within a thunderstorm and the earth’s surface. When the buildup becomes strong enough, lightening appears as a “bolt”.  Lightening’s electrical charge and intense heat can electrocute on contact, split trees, and ignite fires.

Tornado: A tornado is a violently rotating column of air in contact with the ground and extending from the base of a thunderstorm. Tornadoes are categorized by the Enhanced Fujita (EF) scale, which has six categories from zero to five representing increasing degrees of damage.

Microburst: A microburst is a very localized column of sinking air, producing damaging divergent and straight-line winds at the surface that are similar to, but distinguishable from, tornados. The scale and suddenness of a microburst makes it a great danger to aircraft and several fatal crashes have been attributed to the phenomenon over the past decade. Microbursts in forested regions have flattened acres of standing timber.

It Happened in Montana

Former Governor Brian Schweitzer declared a state of emergency after the largest tornado to hit the city of Billings in more than 50 years peeled the roof off of a sports arena, causing millions of dollars in damage on June 20, 2013. No deaths or major injuries were reported. Wind speeds from the tornado were estimated at 111 to 135 mph. The winds damaged homes and snapped trees and telephone poles. The twister hovered for about 15 minutes over the  Metra Arena.


Severe Weather Preparedness: FEMA
Severe Weather Awareness: National Weather Service

Severe Winter Weather

Winter_road_in_Perm_KraiWinter storms are very common in Montana. Winter storms are considered deceptive killers because most deaths are indirectly related to the storm. People die in traffic accidents on snow and ice covered roads, from hypothermia due to prolonged exposure, and heart attacks due to overexertion.

Avalanches are also common hazards in Montana for those recreating outside during the winter months. An avalanche is a mass of loosened snow, ice, and/or earth suddenly and swiftly sliding down a mountain. Avalanches occur throughout the mountains of Montana and, to a limited extent, elsewhere in the state. Avalanche hazards most-directly threaten winter recreationists, homes and businesses in mountainous regions, and communication and transportation networks. Two of Montana’s ski areas, Bridger Bowl and Big Sky, are respectively the second and fourth most avalanche-prone ski resorts in the entire U.S.

It Happened in Montana

In March 2011, a state of emergency was declared by Glacier County and the Blackfeet Tribe due to huge snow drifts and blizzard like conditions. In some areas, snow nearly reached roof tops and covered all windows and doors on homes. In East Glacier, 13 inches fell on top of 51 inches that were already on the ground. Browning had 20 hours of whiteout conditions, stranding motorists.


Severe Winter Storm Preparedness: FEMA
Avalanche Research and Education
Forest Service National Avalanche Center
Montana Disaster and Emergency Survival Guide
Montana Dept. of Transportation Road Report and Travel Information

Communicable Disease

For information on communicable disease in Montana, visit the Department of Public Health and Human Service’s Public Health Emergency Preparedness website by clicking here.

Hazardous Material Incidents

Hazardous materials are chemical substances, which if released or misused can pose a threat to the environment or health. Hazardous materials come in the forms of explosives, flammable and combustible substances, poisons, and radioactive materials. These substances are most often released as a result of transportation accidents or because of chemical accidents in plants.

It Happened in Montana

albertonOn April 11, 1996, 19 cars from a Montana Rail Link freight train derailed near Alberton, Montana. The Governor of Montana declared a state of emergency in Missoula and Mineral counties. Six of the derailed cars contained hazardous materials. This chlorine spill is the second largest in U.S. history. About 1,000 people from the surrounding area were evacuated and approximately 350 people were treated for chlorine inhalation, 123 of whom sustained injury. The hazardous chlorine cloud drifted across I-90, closing the road and resulting in multiple highway traffic accidents and an 81-mile detour. Monetary damage was estimated at $10 million.


Drought is an extended period of below normal precipitation that causes damage to crops and other ground cover. Drought diminishes natural stream flow, depletes soil and subsoil moisture, and because of these effects, causes social, environmental, and economic impacts to Montana.

It Happened in Montana

The period from 1928 to 1939 was the driest in historical record in Montana. The Palmer Hydrologic Drought Index (PHDI) showed the entire state was in a hydrologic deficit for over 10 years. The dust bowl years impacted agricultural production and economies throughout the state.


Montana Drought Information: State of Montana Dept. of Natural Resources and Conservation
National Drought Mitigation Center


The term landslide, as used here, includes all types of gravity-caused mass movements of earth material, ranging from rock falls, slumps, rock slides, mud slides, and debris flows. Landslides occur in all 50 states.

It Happened in Montana

A rain-on-snow event in March 2005 caused a mudslide that severely damaged more than 12 miles of U.S. Highway 212 outside of Red Lodge, Montana. The road is a crucial link to Yellowstone National Park. An Executive Order was issued declaring an emergency for Carbon County. The $15.2 million repair involved excavating rock and slide debris as well as the addition of rock fall fences.


Terrorism is defined in the Code of Federal Regulations as “the unlawful use of force and violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives”. Cyber-terrorism involves computers, networks, and the information they contain. Like other terrorist acts, cyber-terror attacks are typically premeditated, politically motivated, perpetrated by small groups rather than governments, and designed to call attention to a cause, spread fear, or otherwise influence the public and decision-makers.

It Happened in Montana

From 1978 to 1995, Ted Kaczynski, commonly known as the Unabomber, killed three people and injured 22 others across the county with mail bombs while he resided in a cabin near Lincoln, Montana.


Terrorism: U.S. Department of Homeland Security
If You See Something, Say Something Campaign ™

Volcanic Eruptions

Volcanic eruptions are generally not a major concern in Montana due to the relatively low probability compared to other hazards. However, Montana is within a volcanically active region that has experience volcanic activity as recently as 1980 with the eruption of Mount St. Helens in Washington.

It Happened in Montana

old faithfulThe Yellowstone Caldera in Northwestern Wyoming, just south of the Montana border, could pose a serious volcanic threat in the future. A caldera is a term for a large volcanic crater. The Yellowstone caldera is 45 miles across at its greatest diameter. The spectacular geysers, boiling hot springs, and mud pots that have made Yellowstone famous are surface manifestations of a magma chamber at depth.


Yellowstone Volcano Observatory: United States Geological Survey
Volcano Preparedness: Federal Emergency Management Agency






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