Cass County, Iowa Natural Disaster Risk
FEMA National Risk Index assessment · IA
LowComposite Risk Score
National percentile: 60th
Cass County faces low composite natural disaster risk (NRI Risk Index score 60.1, 60th national percentile), driven primarily by drought and cold wave exposure. Expected annual loss across all 18 hazard types is $17M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Cass County carries a low composite natural disaster risk, with a National Risk Index score of 60.1 out of 100 — placing it in the 60th 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.
The county's risk is driven primarily by drought (extended dry periods that stress water supplies and agriculture) at High risk — $3M in expected annual loss and about 8.64 events per year; cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $4M in expected annual loss and about 5.21 events per year; and hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $662K in expected annual loss and about 6.19 events per year. Across all hazards, FEMA estimates $17M in expected annual loss for a population of 13K.
Beyond physical exposure, Cass County has a high 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). Higher vulnerability is partly offset by strong community resilience and recovery capacity.
History supports the rating: Cass County has received 19 federal disaster declarations since 1965, including 7 for flood events and 6 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Tornadoes (severe storm), declared in February 2022.
Among 99 Iowa counties, Cass County ranks #17 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Drought | High | 8.64 / yr | $3M |
| Cold Wave | Medium | 5.21 / yr | $4M |
| Hail | Medium | 6.19 / yr | $662K |
| Tornado | Medium | 0.48 / yr | $3M |
| Heat Wave | Low | 7.32 / yr | $775K |
| Landslide | Low | 0.21 / yr | $3K |
| Strong Wind | Medium | 4.87 / yr | $584K |
| Ice Storm | Low | 0.76 / yr | $88K |
| Winter Weather | Low | 12.53 / yr | $47K |
| Riverine Flood | Low | 1.25 / yr | $4M |
| Wildfire | Very Low | 0.00 / yr | $21K |
| Hurricane | Very Low | 0.01 / yr | $4K |
| Lightning | Very Low | 44.84 / yr | $47K |
| Earthquake | Very Low | 0.00 / yr | $15K |
| 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
Cass County has received 19 federal disaster declarations since 1965, most recently Severe Storms, Straight-Line Winds, and Tornadoes in February 2022. Most frequent causes: Flood (7), Severe Storm (6), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| 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 |
| March 2010 | Severe Storm | Severe Winter Storm |
| February 2010 | Severe Storm | Severe Winter Storms and Snowstorm |
| May 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| May 2007 | Severe Storm | Severe Storms, Flooding, and Tornadoes |
| March 2007 | Snowstorm | Snow |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 19 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Cass County?
Cass County has a composite FEMA National Risk Index score of 60.1 out of 100, placing it in the Low category and the 60th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Cass County?
The three highest-rated hazards are Drought (High, $3M EAL), Cold Wave (Medium, $4M EAL), Hail (Medium, $662K EAL). These account for most of the county's expected annual losses.
How does Cass County compare to other Iowa counties?
Cass County ranks #17 of 99 Iowa counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Cass County had?
FEMA records 19 federal disaster declarations for Cass County since 1965, most often 7 for flood events and 6 for severe storm events. The most recent was Severe Storms, Straight-Line Winds, and Tornadoes, declared in February 2022.
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. Cass County's $17M EAL is a statistical average, not a guarantee for any specific year or address.