Cass County, North Dakota Natural Disaster Risk
FEMA National Risk Index assessment · ND
MediumComposite Risk Score
National percentile: 82th
Cass County faces medium composite natural disaster risk (NRI Risk Index score 82.4, 82th national percentile), driven primarily by winter weather and strong wind exposure. Expected annual loss across all 18 hazard types is $82M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Cass County at medium composite risk, with a National Risk Index score of 82.4 out of 100 — placing it in the 82nd national percentile and near the national midpoint 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 winter weather (heavy snow, blizzards, and hazardous winter conditions) at Very High risk — $4M in expected annual loss and about 24.26 events per year; strong wind (damaging straight-line winds outside of tornadoes and hurricanes) at Very High risk — $10M in expected annual loss and about 2.54 events per year; and hail (ice stones from severe thunderstorms that damage property and crops) at High risk — $7M in expected annual loss and about 4.19 events per year. Across all hazards, FEMA estimates $82M in expected annual loss for a population of 184K.
Beyond physical exposure, Cass County has a very low 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.
The federal record bears this out: Cass County has received 35 federal disaster declarations since 1965, including 22 for flood events and 9 for severe storm events. The most recent was Severe Storm, Tornadoes, and Straight-Line Winds (severe storm), declared in September 2025.
Among 53 North Dakota counties, Cass County ranks #2 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Winter Weather | Very High | 24.26 / yr | $4M |
| Strong Wind | Very High | 2.54 / yr | $10M |
| Hail | High | 4.19 / yr | $7M |
| Ice Storm | Very High | 0.43 / yr | $3M |
| Tornado | Medium | 1.24 / yr | $12M |
| Cold Wave | Medium | 18.58 / yr | $10M |
| Riverine Flood | Medium | 2.18 / yr | $34M |
| Lightning | Medium | 29.59 / yr | $640K |
| Heat Wave | Low | 1.63 / yr | $868K |
| Wildfire | Very Low | 0.00 / yr | $83K |
| Landslide | Very Low | 0.17 / yr | $699 |
| Earthquake | Very Low | 0.00 / yr | $69K |
| Drought | Very Low | 1.57 / yr | $7K |
| 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
Cass County has received 35 federal disaster declarations since 1965, most recently Severe Storm, Tornadoes, and Straight-Line Winds in September 2025. Most frequent causes: Flood (22), Severe Storm (9), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| September 2025 | Severe Storm | Severe Storm, Tornadoes, and Straight-Line Winds |
| February 2024 | Winter Storm | Severe Winter Storm and Straight-Line Winds |
| July 2020 | Flood | Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2019 | Flood | Flooding |
| May 2013 | Flood | Flooding |
| April 2013 | Flood | Flooding |
| May 2011 | Flood | Flooding |
| April 2011 | Flood | Flooding |
Showing the 10 most recent of 35 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 82.4 out of 100, placing it in the Medium category and the 82th 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 Winter Weather (Very High, $4M EAL), Strong Wind (Very High, $10M EAL), Hail (High, $7M EAL). These account for most of the county's expected annual losses.
How does Cass County compare to other North Dakota counties?
Cass County ranks #2 of 53 North Dakota counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Cass County had?
FEMA records 35 federal disaster declarations for Cass County since 1965, most often 22 for flood events and 9 for severe storm events. The most recent was Severe Storm, Tornadoes, and Straight-Line Winds, declared in September 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. Cass County's $82M EAL is a statistical average, not a guarantee for any specific year or address.