Mahaska County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
Very LowComposite Risk Score
National percentile: 30th
Mahaska County faces very low composite natural disaster risk (NRI Risk Index score 29.7, 30th national percentile), driven primarily by drought and strong wind exposure. Expected annual loss across all 18 hazard types is $11M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Mahaska County at very low composite risk, with a National Risk Index score of 29.7 out of 100 — placing it in the 30th 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 Medium risk — $1M in expected annual loss and about 9.10 events per year; strong wind (damaging straight-line winds outside of tornadoes and hurricanes) at Medium risk — $1M in expected annual loss and about 5.76 events per year; and hail (ice stones from severe thunderstorms that damage property and crops) at Low risk — $509K in expected annual loss and about 5.16 events per year. Across all hazards, FEMA estimates $11M in expected annual loss for a population of 22K.
Beyond physical exposure, Mahaska County has a 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.
History supports the rating: Mahaska County has received 20 federal disaster declarations since 1965, including 8 for severe storm events and 7 for flood events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 99 Iowa counties, Mahaska County ranks #66 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | Medium | 9.10 / yr | $1M |
| Strong Wind | Medium | 5.76 / yr | $1M |
| Hail | Low | 5.16 / yr | $509K |
| Landslide | Very Low | 0.15 / yr | $3K |
| Heat Wave | Low | 6.95 / yr | $537K |
| Tornado | Low | 0.47 / yr | $2M |
| Winter Weather | Low | 12.53 / yr | $66K |
| Ice Storm | Low | 0.63 / yr | $76K |
| Wildfire | Very Low | 0.00 / yr | $34K |
| Riverine Flood | Low | 3.96 / yr | $5M |
| Lightning | Low | 44.99 / yr | $152K |
| Cold Wave | Low | 5.63 / yr | $597K |
| Earthquake | Very Low | 0.00 / yr | $81K |
| Hurricane | Very Low | 0.01 / yr | $3K |
| 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
Mahaska County has received 20 federal disaster declarations since 1965, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Severe Storm (8), Flood (7), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| March 2019 | Flood | Severe Storms and Flooding |
| August 2014 | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2013 | Severe Storm | Severe Storms, Tornadoes, 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 |
| September 2007 | Severe Storm | Severe Storms and Flooding |
| March 2007 | Severe Storm | Severe Winter Storms |
Showing the 10 most recent of 20 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Mahaska County?
Mahaska County has a composite FEMA National Risk Index score of 29.7 out of 100, placing it in the Very Low category and the 30th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Mahaska County?
The three highest-rated hazards are Drought (Medium, $1M EAL), Strong Wind (Medium, $1M EAL), Hail (Low, $509K EAL). These account for most of the county's expected annual losses.
How does Mahaska County compare to other Iowa counties?
Mahaska County ranks #66 of 99 Iowa counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Mahaska County had?
FEMA records 20 federal disaster declarations for Mahaska County since 1965, most often 8 for severe storm events and 7 for flood 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. Mahaska County's $11M EAL is a statistical average, not a guarantee for any specific year or address.