Brown County, Wisconsin Natural Disaster Risk
FEMA National Risk Index assessment · WI
MediumComposite Risk Score
National percentile: 90th
Brown County faces medium composite natural disaster risk (NRI Risk Index score 90.0, 90th national percentile), driven primarily by cold wave and hail exposure. Expected annual loss across all 18 hazard types is $104M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Brown County at medium composite risk, with a National Risk Index score of 90.0 out of 100 — placing it in the 90th 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 cold wave (prolonged spells of dangerously low temperatures) at High risk — $25M in expected annual loss and about 5.58 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at High risk — $4M in expected annual loss and about 1.84 events per year; and lightning (electrical discharges from storms that ignite fires and cause casualties) at High risk — $2M in expected annual loss and about 30.87 events per year. Across all hazards, FEMA estimates $104M in expected annual loss for a population of 269K.
Beyond physical exposure, Brown 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: Brown County has received 9 federal disaster declarations since 1973, including 3 for severe storm events and 2 for flood events. The most recent was Severe Storms, Tornadoes, and Flooding (flood), declared in June 2026.
Among 72 Wisconsin counties, Brown County ranks #3 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | High | 5.58 / yr | $25M |
| Hail | High | 1.84 / yr | $4M |
| Lightning | High | 30.87 / yr | $2M |
| Tornado | High | 0.22 / yr | $12M |
| Riverine Flood | Medium | 1.11 / yr | $57M |
| Winter Weather | Medium | 15.84 / yr | $313K |
| Heat Wave | Low | 1.53 / yr | $1M |
| Landslide | Very Low | 0.10 / yr | $3K |
| Ice Storm | Low | 0.21 / yr | $95K |
| Coastal Flood | Low | 0.01 / yr | $69K |
| Earthquake | Very Low | 0.00 / yr | $139K |
| Wildfire | Very Low | 0.00 / yr | $22K |
| Strong Wind | Low | 1.97 / yr | $367K |
| Hurricane | Very Low | 0.01 / yr | $12K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Drought | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Brown County has received 9 federal disaster declarations since 1973, most recently Severe Storms, Tornadoes, and Flooding in June 2026. Most frequent causes: Severe Storm (3), Flood (2), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| June 2026 | Flood | Severe Storms, Tornadoes, and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| June 2004 | Severe Storm | Severe Storms and Flooding |
| July 1993 | Severe Storm | Severe Storms, Tornadoes & Flooding |
| July 1990 | Severe Storm | Severe Storms, Tornadoes & Flooding |
| June 1976 | Drought | Drought |
| April 1973 | Flood | Severe Storms & Flooding |
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Brown County?
Brown County has a composite FEMA National Risk Index score of 90.0 out of 100, placing it in the Medium category and the 90th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Brown County?
The three highest-rated hazards are Cold Wave (High, $25M EAL), Hail (High, $4M EAL), Lightning (High, $2M EAL). These account for most of the county's expected annual losses.
How does Brown County compare to other Wisconsin counties?
Brown County ranks #3 of 72 Wisconsin counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Brown County had?
FEMA records 9 federal disaster declarations for Brown County since 1973, most often 3 for severe storm events and 2 for flood events. The most recent was Severe Storms, Tornadoes, and Flooding, declared in June 2026.
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. Brown County's $104M EAL is a statistical average, not a guarantee for any specific year or address.