Boone County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 28th
Boone County faces very low composite natural disaster risk (NRI Risk Index score 28.4, 28th national percentile), driven primarily by drought and hail exposure. Expected annual loss across all 18 hazard types is $17M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Boone County at very low composite risk, with a National Risk Index score of 28.4 out of 100 — placing it in the 28th 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 Boone County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at High risk — $5M in expected annual loss and about 9.75 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Low risk — $833K in expected annual loss and about 6.14 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Low risk — $162K in expected annual loss and about 15.68 events per year. Across all hazards, FEMA estimates $17M in expected annual loss for a population of 27K.
Beyond physical exposure, Boone County has a very low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The federal record bears this out: Boone County has received 17 federal disaster declarations since 1965, including 8 for severe storm events and 5 for flood events. The most recent was Severe Storms (severe storm), declared in August 2020.
Among 99 Iowa counties, Boone County ranks #69 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 9.75 / yr | $5M |
| Hail | Low | 6.14 / yr | $833K |
| Winter Weather | Low | 15.68 / yr | $162K |
| Tornado | Low | 0.58 / yr | $3M |
| Landslide | Very Low | 0.09 / yr | $3K |
| Cold Wave | Low | 7.84 / yr | $1M |
| Ice Storm | Low | 0.66 / yr | $83K |
| Strong Wind | Low | 5.76 / yr | $670K |
| Riverine Flood | Very Low | 1.71 / yr | $6M |
| Earthquake | Very Low | 0.00 / yr | $35K |
| Wildfire | Very Low | 0.00 / yr | $10K |
| Lightning | Very Low | 43.71 / yr | $82K |
| Hurricane | Very Low | 0.01 / yr | $3K |
| Heat Wave | Very Low | 5.26 / yr | $21K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Boone County has received 17 federal disaster declarations since 1965, most recently Severe Storms in August 2020. Most frequent causes: Severe Storm (8), Flood (5), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| August 2020 | Severe Storm | Severe Storms |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| March 2010 | Severe Storm | Severe Winter Storm |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| September 2007 | Severe Storm | Severe Storms and Flooding |
| March 2007 | Severe Storm | Severe Winter Storms |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 17 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Boone County?
Boone County has a composite FEMA National Risk Index score of 28.4 out of 100, placing it in the Very Low category and the 28th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Boone County?
The three highest-rated hazards are Drought (High, $5M EAL), Hail (Low, $833K EAL), Winter Weather (Low, $162K EAL). These account for most of the county's expected annual losses.
How does Boone County compare to other Iowa counties?
Boone County ranks #69 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Boone County had?
FEMA records 17 federal disaster declarations for Boone County since 1965, most often 8 for severe storm events and 5 for flood events. The most recent was Severe Storms, declared in August 2020.
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. Boone County's $17M EAL is a statistical average, not a guarantee for any specific year or address.