Calhoun County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 45th
Calhoun County faces low composite natural disaster risk (NRI Risk Index score 44.6, 45th national percentile), driven primarily by drought and hail exposure. Expected annual loss across all 18 hazard types is $13M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Calhoun County is low, with a National Risk Index score of 44.6 out of 100 — placing it in the 45th national percentile and below the national average for natural-disaster risk. 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 — $4M in expected annual loss and about 16.87 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $2M in expected annual loss and about 5.67 events per year; and tornado (violently rotating columns of air capable of catastrophic local damage) at Medium risk — $3M in expected annual loss and about 0.52 events per year. Across all hazards, FEMA estimates $13M in expected annual loss for a population of 10K.
Beyond physical exposure, Calhoun County has a medium 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.
History supports the rating: Calhoun County has received 18 federal disaster declarations since 1979, including 9 for severe storm events and 4 for flood events. The most recent was Severe Storms, Tornadoes, and Flooding (severe storm), declared in May 2024.
Among 99 Iowa counties, Calhoun County ranks #32 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 16.87 / yr | $4M |
| Hail | Medium | 5.67 / yr | $2M |
| Tornado | Medium | 0.52 / yr | $3M |
| Strong Wind | Medium | 4.95 / yr | $795K |
| Winter Weather | Medium | 16.00 / yr | $91K |
| Cold Wave | Low | 9.00 / yr | $1M |
| Ice Storm | Low | 0.63 / yr | $69K |
| Riverine Flood | Very Low | 1.79 / yr | $2M |
| Landslide | Very Low | 0.06 / yr | $116 |
| Lightning | Very Low | 42.92 / yr | $65K |
| Heat Wave | Very Low | 4.95 / yr | $46K |
| Hurricane | Very Low | 0.01 / yr | $3K |
| Earthquake | Very Low | 0.00 / yr | $15K |
| Wildfire | Very Low | 0.00 / 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
Calhoun County has received 18 federal disaster declarations since 1979, most recently Severe Storms, Tornadoes, and Flooding in May 2024. Most frequent causes: Severe Storm (9), Flood (4), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| May 2024 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| February 2022 | Severe Storm | Severe Storms, Straight-Line Winds, and Tornadoes |
| 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 |
| February 2010 | Severe Storm | Severe Winter Storms and Snowstorm |
| September 2007 | Severe Storm | Severe Storms and Flooding |
| March 2007 | Severe Storm | Severe Winter Storms |
Showing the 10 most recent of 18 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Calhoun County?
Calhoun County has a composite FEMA National Risk Index score of 44.6 out of 100, placing it in the Low category and the 45th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Calhoun County?
The three highest-rated hazards are Drought (High, $4M EAL), Hail (Medium, $2M EAL), Tornado (Medium, $3M EAL). These account for most of the county's expected annual losses.
How does Calhoun County compare to other Iowa counties?
Calhoun County ranks #32 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Calhoun County had?
FEMA records 18 federal disaster declarations for Calhoun County since 1979, most often 9 for severe storm events and 4 for flood events. The most recent was Severe Storms, Tornadoes, and Flooding, 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. Calhoun County's $13M EAL is a statistical average, not a guarantee for any specific year or address.