Brown County, Wisconsin: Natural Disaster Risk and History
Brown County, Wisconsin has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 90.0 out of 100, higher than about 90% of US counties, with cold waves, hail and lightning scoring highest of its 18 hazards and $104 million a year in expected losses.
OpenFEMA lists 7 federal disaster declarations that included Brown County since 1973, not counting 2 for COVID-19; the latest is DR-4923-WI (Severe Storms, Tornadoes, and Flooding, declared 30 June 2026). NOAA's Storm Prediction Center recorded 31 tornadoes touching Brown County from 1950 to 2025.
Live weather alerts for Wisconsin All official warnings Latest FEMA declarations
Population 268,585 Buildings worth $86 billion Area 622 sq mi Risk rank in Wisconsin 3 of 72 FIPS 55009
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Cold wave | Relatively High | 98.1 | $25 million | about 5.6 a year | 106 |
| Hail | Relatively High | 95.7 | $4.1 million | about 1.8 a year | 79 |
| Lightning | Relatively High | 95.0 | $2.3 million | about 31 a year | 181,088 strikes |
| Tornado | Relatively High | 93.4 | $12 million | about once every 4.5 years | 20 |
| Inland flooding | Relatively Moderate | 91.9 | $57 million | about 1.1 a year | 31 |
| Winter weather | Relatively Moderate | 83.9 | $312,548 | about 16 a year | 301 |
| Heat wave | Relatively Low | 76.0 | $1.5 million | about 1.5 a year | 22 |
| Landslide | Very Low | 57.8 | $2,862 | about once every 10 years | — |
| Ice storm | Relatively Low | 47.8 | $95,211 | about once every 4.9 years | 14 |
| Coastal flooding | Relatively Low | 46.4 | $69,312 | about once every 75 years | — |
| Earthquake | Very Low | 35.3 | $138,795 | rarer than once in 1,000 years | — |
| Wildfire | Very Low | 33.8 | $22,140 | rarer than once in 1,000 years | — |
| Strong wind | Relatively Low | 31.0 | $367,166 | about 2 a year | 74 |
| Hurricane | Very Low | 26.1 | $12,482 | about once every 100 years | 0 |
| Drought | No Rating | 0.0 | — | — | 0 |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Insufficient Data | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 7
Most common: Severe Storm 3, Flood 2, Hurricane 1, Drought 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 2 | Drought, Flood |
| 1990s | 2 | Severe Storm ×2 |
| 2000s | 2 | Hurricane, Severe Storm |
| 2020s | 1 | Flood |
The last 7
Widest declarations that included Brown County
- Hurricane Katrina Evacuation (2005, EM-3249-WI): 72 Wisconsin counties designated.
- Drought (1976, EM-3014-WI): 66 Wisconsin counties designated.
- Severe Storms, Tornadoes & Flooding (1993, DR-994-WI): 47 Wisconsin counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Wisconsin also had 1 statewide declaration with no county list.
Tornado record since 1950 31
| Tornadoes touching the county | 31 |
|---|---|
| Strongest-rated | (E)F3 ×1 |
| Peak month | August (10) |
| Deadliest | 10 May 1959, F2, 4.3 mi path, 0 killed, 3 injured |
| Longest path | 6 Aug 2013, EF1, 33.1 mi path |
| Most recent | 11 Aug 2021, EF0, 2.3 mi path |
| Deaths / injuries on those paths | 0 / 8 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 13 | 13 | 4 | 1 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 5 | 4 | 7 | 0 | 2 | 3 | 9 | 1 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Brown County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Brown County (this page) | — | Relatively Moderate | 90.0 | Cold wave |
| Kewaunee County | 32 km | Very Low | 17.3 | Cold wave |
| Outagamie County | 37 km | Relatively Low | 79.7 | Cold wave |
| Manitowoc County | 40 km | Relatively Low | 68.9 | Hail |
| Calumet County | 45 km | Very Low | 30.2 | Hail |
| Winnebago County | 67 km | Relatively Moderate | 86.8 | Cold wave |
Nearest by distance between county centres. Every county in Wisconsin, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 17.5 |
|---|---|
| Community resilience | Very High 94.9 |
| Community risk factor | 0.85 |
| Expected annual loss, all hazards | $104 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Brown County's main hazards
- Right now: National Weather Service alerts for Wisconsin · all official warnings on Global Incident Tracker.
- Cold wave: Carbon monoxide in winter · Power outages now
- Hail: Weather alerts for Wisconsin
- Lightning: Weather alerts for Wisconsin
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Brown County
What natural disasters is Brown County, Wisconsin most at risk from?
Brown County, Wisconsin has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 90.0 out of 100, higher than about 90% of US counties, with cold waves, hail and lightning scoring highest of its 18 hazards and $104 million a year in expected losses.
How many federal disaster declarations has Brown County had?
OpenFEMA lists 7 federal disaster declarations that included Brown County since 1973, not counting 2 for COVID-19; the latest is DR-4923-WI (Severe Storms, Tornadoes, and Flooding, declared 30 June 2026). Another 1 Wisconsin declarations were made statewide without a county list.
How many tornadoes have hit Brown County?
NOAA's Storm Prediction Center recorded 31 tornadoes touching Brown County from 1950 to 2025. The deadliest: 10 May 1959, F2, 4.3 mi path, 0 killed, 3 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.