Rock County, Minnesota Natural Disaster Risk
FEMA National Risk Index assessment · MN
Very LowComposite Risk Score
National percentile: 9th
Rock County faces very low composite natural disaster risk (NRI Risk Index score 9.4, 9th national percentile), driven primarily by hail and winter weather exposure. Expected annual loss across all 18 hazard types is $7M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Rock County at very low composite risk, with a National Risk Index score of 9.4 out of 100 — placing it in the 9th 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.
Most of Rock County's expected losses come from hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $996K in expected annual loss and about 5.88 events per year; winter weather (heavy snow, blizzards, and hazardous winter conditions) at Medium risk — $160K in expected annual loss and about 18.42 events per year; and drought (extended dry periods that stress water supplies and agriculture) at Low risk — $332K in expected annual loss and about 11.26 events per year. Across all hazards, FEMA estimates $7M in expected annual loss for a population of 10K.
Beyond physical exposure, Rock 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 federal record bears this out: Rock County has received 16 federal disaster declarations since 1969, including 6 for flood events and 6 for severe storm events. The most recent was Severe Storms and Flooding (flood), declared in June 2024.
Among 87 Minnesota counties, Rock County ranks #77 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Medium | 5.88 / yr | $996K |
| Winter Weather | Medium | 18.42 / yr | $160K |
| Drought | Low | 11.26 / yr | $332K |
| Ice Storm | Low | 1.16 / yr | $153K |
| Cold Wave | Low | 9.74 / yr | $865K |
| Tornado | Low | 0.40 / yr | $1M |
| Heat Wave | Very Low | 4.05 / yr | $107K |
| Strong Wind | Low | 4.09 / yr | $290K |
| Landslide | Very Low | 0.05 / yr | $154 |
| Riverine Flood | Very Low | 1.68 / yr | $3M |
| Wildfire | Very Low | 0.00 / yr | $3K |
| Earthquake | Very Low | 0.00 / yr | $10K |
| Lightning | Very Low | 38.60 / 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
Rock County has received 16 federal disaster declarations since 1969, most recently Severe Storms and Flooding in June 2024. Most frequent causes: Flood (6), Severe Storm (6), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| June 2024 | Flood | Severe Storms and Flooding |
| August 2022 | Severe Storm | Severe Storms, Straight-Line Winds, Tornadoes, and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2019 | Flood | Severe Winter Storm, Straight-Line Winds, and Flooding |
| September 2018 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2014 | Flood | Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides |
| May 2013 | Severe Storm | Severe Winter Storm |
| October 2010 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
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 Rock County?
Rock County has a composite FEMA National Risk Index score of 9.4 out of 100, placing it in the Very Low category and the 9th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Rock County?
The three highest-rated hazards are Hail (Medium, $996K EAL), Winter Weather (Medium, $160K EAL), Drought (Low, $332K EAL). These account for most of the county's expected annual losses.
How does Rock County compare to other Minnesota counties?
Rock County ranks #77 of 87 Minnesota counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Rock County had?
FEMA records 16 federal disaster declarations for Rock County since 1969, most often 6 for flood events and 6 for severe storm events. The most recent was Severe Storms and Flooding, declared in June 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. Rock County's $7M EAL is a statistical average, not a guarantee for any specific year or address.