Harrison County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 31th
Harrison County faces very low composite natural disaster risk (NRI Risk Index score 31.3, 31th national percentile), driven primarily by drought and hail exposure. Expected annual loss across all 18 hazard types is $10M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Harrison County is very low, with a National Risk Index score of 31.3 out of 100 — placing it in the 31st 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 Harrison County's expected losses come from drought (extended dry periods that stress water supplies and agriculture) at Medium risk — $1M in expected annual loss and about 19.03 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $1M in expected annual loss and about 6.39 events per year; and landslide (downhill movement of rock, soil, and debris on unstable slopes) at Low risk — $27K in expected annual loss and about 0.44 events per year. Across all hazards, FEMA estimates $10M in expected annual loss for a population of 15K.
Beyond physical exposure, Harrison County has a medium social vulnerability rating (how susceptible the population is to harm) and a 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: Harrison County has received 24 federal disaster declarations since 1965, including 9 for severe storm events and 9 for flood events. The most recent was Severe Winter Storm (winter storm), declared in May 2025.
Among 99 Iowa counties, Harrison County ranks #61 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Medium | 19.03 / yr | $1M |
| Hail | Medium | 6.39 / yr | $1M |
| Landslide | Low | 0.44 / yr | $27K |
| Tornado | Low | 0.56 / yr | $2M |
| Wildfire | Very Low | 0.00 / yr | $80K |
| Strong Wind | Medium | 4.50 / yr | $627K |
| Ice Storm | Low | 0.89 / yr | $96K |
| Riverine Flood | Low | 0.89 / yr | $4M |
| Winter Weather | Low | 14.26 / yr | $37K |
| Cold Wave | Low | 5.63 / yr | $379K |
| Heat Wave | Very Low | 6.42 / yr | $56K |
| Lightning | Very Low | 44.16 / yr | $55K |
| Earthquake | Very Low | 0.00 / yr | $12K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| 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
Harrison County has received 24 federal disaster declarations since 1965, most recently Severe Winter Storm in May 2025. Most frequent causes: Severe Storm (9), Flood (9), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| May 2025 | Winter Storm | Severe Winter Storm |
| June 2024 | Severe Storm | Severe Storms, Flooding, Straight-Line Winds, and Tornadoes |
| May 2024 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| May 2024 | Tornado | Severe Storms and Tornadoes |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| June 2011 | Flood | Flooding |
| March 2010 | Severe Storm | Severe Winter Storm |
| February 2010 | Severe Storm | Severe Winter Storms and Snowstorm |
Showing the 10 most recent of 24 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Harrison County?
Harrison County has a composite FEMA National Risk Index score of 31.3 out of 100, placing it in the Very Low category and the 31th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Harrison County?
The three highest-rated hazards are Drought (Medium, $1M EAL), Hail (Medium, $1M EAL), Landslide (Low, $27K EAL). These account for most of the county's expected annual losses.
How does Harrison County compare to other Iowa counties?
Harrison County ranks #61 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Harrison County had?
FEMA records 24 federal disaster declarations for Harrison County since 1965, most often 9 for severe storm events and 9 for flood events. The most recent was Severe Winter Storm, declared in May 2025.
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. Harrison County's $10M EAL is a statistical average, not a guarantee for any specific year or address.