Decatur County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 24th
Decatur County faces very low composite natural disaster risk (NRI Risk Index score 23.6, 24th national percentile), driven primarily by drought and landslide exposure. Expected annual loss across all 18 hazard types is $8M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Decatur County carries a very low composite natural disaster risk, with a National Risk Index score of 23.6 out of 100 — placing it in the 24th 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 Decatur County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at High risk — $2M in expected annual loss and about 12.39 events per year; landslide (downhill movement of rock, soil, and debris on unstable slopes) at Low risk — $7K in expected annual loss and about 0.39 events per year; and heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Low risk — $660K in expected annual loss and about 7.74 events per year. Across all hazards, FEMA estimates $8M in expected annual loss for a population of 8K.
Beyond physical exposure, Decatur County has a medium social vulnerability rating (how susceptible the population is to harm) and a medium 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: Decatur County has received 14 federal disaster declarations since 1969, including 6 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 99 Iowa counties, Decatur County ranks #79 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 12.39 / yr | $2M |
| Landslide | Low | 0.39 / yr | $7K |
| Heat Wave | Low | 7.74 / yr | $660K |
| Cold Wave | Low | 4.42 / yr | $1M |
| Wildfire | Very Low | 0.00 / yr | $51K |
| Tornado | Low | 0.38 / yr | $1M |
| Hail | Low | 5.38 / yr | $229K |
| Strong Wind | Low | 4.61 / yr | $413K |
| Ice Storm | Very Low | 0.39 / yr | $20K |
| Earthquake | Very Low | 0.00 / yr | $24K |
| Lightning | Very Low | 45.63 / yr | $55K |
| Winter Weather | Very Low | 11.53 / yr | $13K |
| Riverine Flood | Very Low | 1.82 / yr | $2M |
| Hurricane | Very Low | 0.01 / yr | $1K |
| 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
Decatur County has received 14 federal disaster declarations since 1969, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Flood (6), Severe Storm (4), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| July 2014 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| May 2013 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| July 2010 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| January 2008 | Severe Ice Storm | Severe Winter Storm |
| May 2007 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 14 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Decatur County?
Decatur County has a composite FEMA National Risk Index score of 23.6 out of 100, placing it in the Very Low category and the 24th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Decatur County?
The three highest-rated hazards are Drought (High, $2M EAL), Landslide (Low, $7K EAL), Heat Wave (Low, $660K EAL). These account for most of the county's expected annual losses.
How does Decatur County compare to other Iowa counties?
Decatur County ranks #79 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Decatur County had?
FEMA records 14 federal disaster declarations for Decatur County since 1969, most often 6 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic, declared in March 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. Decatur County's $8M EAL is a statistical average, not a guarantee for any specific year or address.