Lewis County, Idaho Natural Disaster Risk
FEMA National Risk Index assessment · ID
Very LowComposite Risk Score
National percentile: 3th
Lewis County faces very low composite natural disaster risk (NRI Risk Index score 3.1, 3th national percentile), driven primarily by wildfire and avalanche exposure. Expected annual loss across all 18 hazard types is $2M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Lewis County is very low, with a National Risk Index score of 3.1 out of 100 — placing it in the 3rd 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.
The county's risk is driven primarily by wildfire (uncontrolled fires that spread across wildland and into communities) at Low risk — $628K in expected annual loss and about 0.01 events per year; avalanche (fast-moving snow and debris sliding down steep mountain slopes) at Very Low risk — $2K in expected annual loss and about 0.01 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Very Low risk — $519 in expected annual loss and about 0.19 events per year. Across all hazards, FEMA estimates $2M in expected annual loss for a population of 4K.
Beyond physical exposure, Lewis County has a high 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). That combination — a more vulnerable population with limited resilience — can amplify the human cost of any given event.
History supports the rating: Lewis County has received 12 federal disaster declarations since 1964, including 3 for flood events and 3 for fire events. The most recent was Straight-Line Winds (straight-line winds), declared in April 2026.
Among 44 Idaho counties, Lewis County ranks #42 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Wildfire | Low | 0.01 / yr | $628K |
| Avalanche | Very Low | 0.01 / yr | $2K |
| Landslide | Very Low | 0.19 / yr | $519 |
| Earthquake | Very Low | 0.00 / yr | $31K |
| Heat Wave | Very Low | 3.68 / yr | $47K |
| Drought | Very Low | 15.86 / yr | $608 |
| Riverine Flood | Very Low | 0.14 / yr | $1M |
| Cold Wave | Very Low | 0.26 / yr | $56K |
| Hail | Very Low | 0.32 / yr | $20K |
| Tornado | Very Low | 0.01 / yr | $5K |
| Winter Weather | Very Low | 19.95 / yr | $1K |
| Strong Wind | Very Low | 0.19 / yr | $11K |
| Lightning | Very Low | 18.53 / yr | $6K |
| Ice Storm | Very Low | 0.01 / yr | $419 |
| 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
Lewis County has received 12 federal disaster declarations since 1964, most recently Straight-Line Winds in April 2026. Most frequent causes: Flood (3), Fire (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| April 2026 | Straight-Line Winds | Straight-Line Winds |
| June 2024 | Flood | Severe Storm, Flooding, Landslides, and Mudslides |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2019 | Flood | Severe Storms, Flooding, Landslides, and Mudslides |
| August 2015 | Fire | Clearwater Lawyer Branch Fire Complex |
| July 2010 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina |
| September 2000 | Fire | Wildfires |
| February 1996 | Severe Storm | Severe Storms and Flooding |
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 Lewis County?
Lewis County has a composite FEMA National Risk Index score of 3.1 out of 100, placing it in the Very Low category and the 3th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Lewis County?
The three highest-rated hazards are Wildfire (Low, $628K EAL), Avalanche (Very Low, $2K EAL), Landslide (Very Low, $519 EAL). These account for most of the county's expected annual losses.
How does Lewis County compare to other Idaho counties?
Lewis County ranks #42 of 44 Idaho counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Lewis County had?
FEMA records 12 federal disaster declarations for Lewis County since 1964, most often 3 for flood events and 3 for fire events. The most recent was Straight-Line Winds, declared in April 2026.
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. Lewis County's $2M EAL is a statistical average, not a guarantee for any specific year or address.