riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

Custer County Disaster Risk

Custer County, Idaho

FEMA Risk Rating

Relatively Low

National Percentile

52th

of 3,144 counties

State Rank

#13

of 44 (1 = highest risk)

Flood Risk

57th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively Low

Higher than 57% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Moderate

Higher than 87% of US counties

Tornado

Tornado and severe thunderstorm risk

Very Low

Higher than 3% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively Low

Higher than 79% of US counties

Risk Overview

About Natural Disaster Risk in Custer County, Idaho

Custer County faces elevated national risk

With a composite risk score of 52.42 and a Relatively Low rating, Custer County exceeds the national average for natural disaster hazards. The county's mountainous terrain and remote location create multiple exposure points.

Among Idaho's higher-risk counties

Custer County's score of 52.42 ranks significantly above Idaho's state average of 38.51, placing it in the upper tier of state risk. Only a few Idaho counties experience comparable or greater cumulative hazard exposure.

Earthquake and wildfire define the region

Custer County's earthquake risk of 79.29 is the highest among regional neighbors, while its wildfire risk of 87.02 places it alongside other central Idaho counties. This combination reflects the county's position atop active seismic zones and extensive forests.

Earthquake and wildfire pose greatest threats

Custer County residents face earthquake risk of 79.29 and wildfire risk of 87.02, while flood (57.32) and tornado (2.99) pose secondary concerns. The county's mountain location amplifies both seismic and forest fire exposure.

Earthquakes require structural preparation

Beyond standard homeowners coverage, Custer County properties benefit from earthquake insurance and wildfire riders given the county's dual-hazard exposure. Foundation bolting and wildfire-resistant landscaping are also critical investments for long-term protection.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in Custer County

Top Hazards by Exposure

  1. #1
    WildfirePrepare
    87th percentile
  2. #2
    EarthquakePrepare
    79th percentile
  3. #3
    FloodPrepare
    57th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Risk Advisory: Custer County

Risk Verdict

Custer County has a below-average natural disaster risk profile, scoring at the 52th percentile nationally under FEMA's National Risk Index. Households in Custer County benefit from knowing which individual hazard types — flood, wildfire, tornado, or hurricane — are the primary contributors.

Hazard Breakdown

Wildfire risk is Custer County's dominant natural hazard, ranked at the 87th percentile nationally under FEMA's National Risk Index. Earthquake ranks second at the 79th percentile nationally. Additional tracked hazards include flood (57th percentile), tornado (3th percentile).

Preparedness Context

Wildfire is Custer County's top-ranked natural hazard at the 87th percentile nationally. Custer County residents should assess whether their property lies within or adjacent to a Wildland-Urban Interface (WUI) zone, where ember transport and rapid spread pose the highest risk. A secondary earthquake exposure at the 79th percentile nationally means Custer County residents face hazards from two distinct natural peril categories during different seasons. For Custer County households, a practiced evacuation plan — with a primary and backup route designated before a fire occurs — provides more protection than any structural improvement when a wildfire approaches fast-moving terrain.

Regional Context

Custer County's composite risk score sits 13.9 points above the Idaho county average, placing it among the more hazard-exposed counties in the state.

Is your household prepared for Custer County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in Custer County, ID?
Custer County has a FEMA National Risk Index rating of Relatively Low, placing it in the 52th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.
What types of natural hazards affect Custer County?
Custer County is evaluated for five major natural hazard types: wildfire (87th percentile), earthquake (79th percentile), flooding (57th percentile), tornado (3th percentile). The highest-risk hazard is wildfire at the 87th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.
How does Custer County risk compare to the Idaho average?
Custer County's composite risk percentile is 52th, compared to the Idaho state average of 39th percentile. The state's overall risk rating is Very Low. This means Custer County faces higher natural disaster risk than the typical county in Idaho.
Is Custer County at risk for wildfire?
Yes, Custer County's wildfire risk is at the 87th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Custer County is at the 57th percentile.
How is natural disaster risk measured?
FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.
Why is Custer County higher risk than average?
Custer County's composite risk score of 52th percentile is above the Idaho state average of 39th percentile. This elevated risk is driven by wildfire exposure (87th percentile), along with earthquake and flooding risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.
By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.