Clarke County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 18th
Clarke County faces very low composite natural disaster risk (NRI Risk Index score 18.4, 18th national percentile), driven primarily by drought and landslide exposure. Expected annual loss across all 18 hazard types is $10M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Clarke County at very low composite risk, with a National Risk Index score of 18.4 out of 100 — placing it in the 18th 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.
Risk here concentrates in drought (extended dry periods that stress water supplies and agriculture) at High risk — $3M in expected annual loss and about 10.34 events per year; landslide (downhill movement of rock, soil, and debris on unstable slopes) at Low risk — $7K in expected annual loss and about 0.28 events per year; and cold wave (prolonged spells of dangerously low temperatures) at Low risk — $2M in expected annual loss and about 4.84 events per year. Across all hazards, FEMA estimates $10M in expected annual loss for a population of 10K.
Beyond physical exposure, Clarke County has a very low 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 county's disaster history tells the same story: Clarke County has received 16 federal disaster declarations since 1969, including 6 for flood events and 4 for severe storm events. The most recent was Severe Storms and Tornadoes (tornado), declared in May 2024.
Among 99 Iowa counties, Clarke County ranks #88 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 10.34 / yr | $3M |
| Landslide | Low | 0.28 / yr | $7K |
| Cold Wave | Low | 4.84 / yr | $2M |
| Heat Wave | Low | 7.63 / yr | $656K |
| Hail | Low | 5.76 / yr | $314K |
| Tornado | Low | 0.34 / yr | $1M |
| Wildfire | Very Low | 0.00 / yr | $43K |
| Strong Wind | Low | 5.11 / yr | $502K |
| Ice Storm | Low | 0.60 / yr | $58K |
| Winter Weather | Very Low | 11.68 / yr | $29K |
| Earthquake | Very Low | 0.00 / yr | $23K |
| Riverine Flood | Very Low | 1.82 / yr | $2M |
| Lightning | Very Low | 45.00 / yr | $46K |
| 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
Clarke County has received 16 federal disaster declarations since 1969, most recently Severe Storms and Tornadoes in May 2024. Most frequent causes: Flood (6), Severe Storm (4), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| May 2024 | Tornado | Severe Storms and Tornadoes |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2014 | Severe Storm | Severe Storms, Tornadoes, 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 |
| July 1998 | Flood | Severe Storms, Tornadoes and Flooding |
Showing the 10 most recent of 16 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Clarke County?
Clarke County has a composite FEMA National Risk Index score of 18.4 out of 100, placing it in the Very Low category and the 18th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Clarke County?
The three highest-rated hazards are Drought (High, $3M EAL), Landslide (Low, $7K EAL), Cold Wave (Low, $2M EAL). These account for most of the county's expected annual losses.
How does Clarke County compare to other Iowa counties?
Clarke County ranks #88 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Clarke County had?
FEMA records 16 federal disaster declarations for Clarke County since 1969, most often 6 for flood events and 4 for severe storm events. The most recent was Severe Storms and Tornadoes, declared in May 2024.
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. Clarke County's $10M EAL is a statistical average, not a guarantee for any specific year or address.