Petroleum County, Montana Natural Disaster Risk
FEMA National Risk Index assessment · MT
Very LowComposite Risk Score
National percentile: 1th
Petroleum County faces very low composite natural disaster risk (NRI Risk Index score 1.3, 1th national percentile), driven primarily by lightning and wildfire exposure. Expected annual loss across all 18 hazard types is $2M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Petroleum County carries a very low composite natural disaster risk, with a National Risk Index score of 1.3 out of 100 — placing it in the 1st national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Petroleum County's expected losses come from lightning (electrical discharges from storms that ignite fires and cause casualties) at Medium risk — $538K in expected annual loss and about 28.75 events per year; wildfire (uncontrolled fires that spread across wildland and into communities) at Low risk — $142K in expected annual loss and about 0.00 events per year; and cold wave (prolonged spells of dangerously low temperatures) at Low risk — $505K in expected annual loss and about 7.69 events per year. Across all hazards, FEMA estimates $2M in expected annual loss for a population of 496.
Beyond physical exposure, Petroleum County has a low social vulnerability rating (how susceptible the population is to harm) and a very low community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
The federal record bears this out: Petroleum County has received 12 federal disaster declarations since 1986, including 4 for flood events and 3 for severe storm events. The most recent was Severe Winter Storm and Flooding (severe storm), declared in July 2024.
Among 56 Montana counties, Petroleum County ranks #54 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Lightning | Medium | 28.75 / yr | $538K |
| Wildfire | Low | 0.00 / yr | $142K |
| Cold Wave | Low | 7.69 / yr | $505K |
| Drought | Very Low | 70.94 / yr | $2K |
| Landslide | Very Low | 0.77 / yr | $55 |
| Winter Weather | Very Low | 16.79 / yr | $11K |
| Hail | Very Low | 1.35 / yr | $31K |
| Heat Wave | Very Low | 2.90 / yr | $7K |
| Tornado | Very Low | 0.11 / yr | $5K |
| Riverine Flood | Very Low | 0.82 / yr | $398K |
| Earthquake | Very Low | 0.00 / yr | $2K |
| Strong Wind | Very Low | 0.70 / yr | $6K |
| Ice Storm | Very Low | 0.01 / yr | $353 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Petroleum County has received 12 federal disaster declarations since 1986, most recently Severe Winter Storm and Flooding in July 2024. Most frequent causes: Flood (4), Severe Storm (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2024 | Severe Storm | Severe Winter Storm and Flooding |
| October 2023 | Flood | Flooding |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| August 2018 | Flood | Flooding |
| July 2017 | Fire | Lodgepole Fire Complex |
| October 2014 | Severe Storm | Severe Storms, Straight-Line Winds, and Flooding |
| July 2013 | Flood | Flooding |
| June 2011 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 12 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Petroleum County?
Petroleum County has a composite FEMA National Risk Index score of 1.3 out of 100, placing it in the Very Low category and the 1th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Petroleum County?
The three highest-rated hazards are Lightning (Medium, $538K EAL), Wildfire (Low, $142K EAL), Cold Wave (Low, $505K EAL). These account for most of the county's expected annual losses.
How does Petroleum County compare to other Montana counties?
Petroleum County ranks #54 of 56 Montana counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Petroleum County had?
FEMA records 12 federal disaster declarations for Petroleum County since 1986, most often 4 for flood events and 3 for severe storm events. The most recent was Severe Winter Storm and Flooding, declared in July 2024.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Petroleum County's $2M EAL is a statistical average, not a guarantee for any specific year or address.