Gem County, Idaho Natural Disaster Risk
FEMA National Risk Index assessment · ID
Very LowComposite Risk Score
National percentile: 34th
Gem County faces very low composite natural disaster risk (NRI Risk Index score 34.4, 34th national percentile), driven primarily by wildfire and winter weather exposure. Expected annual loss across all 18 hazard types is $11M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Gem County at very low composite risk, with a National Risk Index score of 34.4 out of 100 — placing it in the 34th 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 Gem County's expected losses come from wildfire (uncontrolled fires that spread across wildland and into communities) at Medium risk — $6M in expected annual loss and about 0.02 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Low risk — $74K in expected annual loss and about 11.81 events per year; and earthquake (ground shaking from sudden movement along geologic faults) at Very Low risk — $295K in expected annual loss and about 0.00 events per year. Across all hazards, FEMA estimates $11M in expected annual loss for a population of 19K.
Beyond physical exposure, Gem County has a low social vulnerability rating (how susceptible the population is to harm) and a 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: Gem County has received 7 federal disaster declarations since 1964, including 2 for biological events and 2 for severe storm events. The most recent was Four Corners Fire (fire), declared in August 2022.
Among 44 Idaho counties, Gem County ranks #24 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Wildfire | Medium | 0.02 / yr | $6M |
| Winter Weather | Low | 11.81 / yr | $74K |
| Earthquake | Very Low | 0.00 / yr | $295K |
| Avalanche | Very Low | 0.03 / yr | $540 |
| Landslide | Very Low | 0.46 / yr | $1K |
| Volcanic Activity | Very Low | 0.00 / yr | $9 |
| Heat Wave | Low | 3.46 / yr | $284K |
| Riverine Flood | Low | 0.36 / yr | $4M |
| Strong Wind | Low | 0.32 / yr | $233K |
| Ice Storm | Very Low | 0.04 / yr | $22K |
| Lightning | Very Low | 20.85 / yr | $69K |
| Drought | Very Low | 12.54 / yr | $77 |
| Cold Wave | Very Low | 0.05 / yr | $34K |
| Tornado | Very Low | 0.03 / yr | $26K |
| Hail | Very Low | 0.23 / yr | $12K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
Disaster History
Gem County has received 7 federal disaster declarations since 1964, most recently Four Corners Fire in August 2022. Most frequent causes: Biological (2), Severe Storm (2), Fire (1).
| Declared | Type | Disaster |
|---|---|---|
| August 2022 | Fire | Four Corners Fire |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2010 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina |
| January 1997 | Severe Storm | Severe Storms, Flooding, Mud and Landslides |
| December 1964 | Flood | Heavy Rains & Flooding |
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Gem County?
Gem County has a composite FEMA National Risk Index score of 34.4 out of 100, placing it in the Very Low category and the 34th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Gem County?
The three highest-rated hazards are Wildfire (Medium, $6M EAL), Winter Weather (Low, $74K EAL), Earthquake (Very Low, $295K EAL). These account for most of the county's expected annual losses.
How does Gem County compare to other Idaho counties?
Gem County ranks #24 of 44 Idaho counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Gem County had?
FEMA records 7 federal disaster declarations for Gem County since 1964, most often 2 for biological events and 2 for severe storm events. The most recent was Four Corners Fire, declared in August 2022.
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. Gem County's $11M EAL is a statistical average, not a guarantee for any specific year or address.