Waukesha County, Wisconsin: Natural Disaster Risk and History
Waukesha County, Wisconsin has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 88.9 out of 100, higher than about 88% of US counties, with cold waves, hail and tornadoes scoring highest of its 18 hazards and $138 million a year in expected losses.
OpenFEMA lists 17 federal disaster declarations that included Waukesha County since 1969, 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 39 tornadoes touching Waukesha County from 1950 to 2025.
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Population 406,817 Buildings worth $110 billion Area 586 sq mi Risk rank in Wisconsin 4 of 72 FIPS 55133
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 | 97.4 | $30 million | about 5.3 a year | 101 |
| Hail | Relatively High | 96.1 | $6.4 million | about 3.7 a year | 140 |
| Tornado | Relatively High | 95.7 | $24 million | about once every 2.7 years | 26 |
| Heat wave | Relatively Moderate | 90.4 | $5.7 million | about 3.2 a year | 51 |
| Inland flooding | Relatively Moderate | 89.8 | $68 million | about 1.8 a year | 49 |
| Winter weather | Relatively High | 86.5 | $553,199 | about 15 a year | 286 |
| Ice storm | Relatively Moderate | 81.7 | $841,202 | about once every 1.6 years | 42 |
| Landslide | Relatively Low | 62.5 | $5,776 | about once every 8.2 years | — |
| Lightning | Relatively Moderate | 60.2 | $606,416 | about 36 a year | 337,381 strikes |
| Earthquake | Very Low | 57.4 | $724,234 | rarer than once in 1,000 years | — |
| Strong wind | Relatively Moderate | 56.1 | $1.2 million | about 4.1 a year | 157 |
| Wildfire | Very Low | 49.7 | $83,382 | rarer than once in 1,000 years | — |
| Drought | Relatively Low | 31.6 | $54,656 | about 1.2 a year | 77 |
| Hurricane | Very Low | 9.7 | $3,165 | about once every 142 years | 2 |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| 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 17
Most common: Flood 7, Severe Storm 6, Snowstorm 2, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 1 | Flood |
| 1970s | 3 | Flood ×2, Drought |
| 1980s | 2 | Flood ×2 |
| 1990s | 3 | Severe Storm ×3 |
| 2000s | 6 | Severe Storm ×3, Snowstorm ×2, Hurricane |
| 2020s | 2 | Flood ×2 |
The last 10
Widest declarations that included Waukesha County
- Hurricane Katrina Evacuation (2005, EM-3249-WI): 72 Wisconsin counties designated.
- Drought (1976, EM-3014-WI): 66 Wisconsin counties designated.
- Severe Storms and Flooding (2004, DR-1526-WI): 44 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 39
| Tornadoes touching the county | 39 |
|---|---|
| Strongest-rated | (E)F4 ×1 |
| Peak month | July (12) |
| Deadliest | 27 Apr 1984, F4, 6.5 mi path, 1 killed, 14 injured |
| Longest path | 5 Jun 1977, F3, 69.5 mi path, 0 killed, 8 injured |
| Most recent | 28 Jul 2023, EF1, 1.3 mi path |
| Deaths / injuries on those paths | 1 / 43 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 8 | 21 | 7 | 2 | 1 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 4 | 5 | 5 | 9 | 1 | 2 | 6 | 7 |
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 Waukesha County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Waukesha County (this page) | — | Relatively Moderate | 88.9 | Cold wave |
| Milwaukee County | 27 km | Relatively High | 98.4 | Cold wave |
| Racine County | 36 km | Relatively Moderate | 85.4 | Cold wave |
| Jefferson County | 38 km | Relatively Low | 75.8 | Hail |
| Washington County | 39 km | Relatively Low | 68.3 | Cold wave |
| Walworth County | 43 km | Relatively Low | 74.8 | Hail |
Nearest by distance between county centres. Every county in Wisconsin, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 10.6 |
|---|---|
| Community resilience | Very High 97.4 |
| Community risk factor | 0.58 |
| Expected annual loss, all hazards | $138 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 Waukesha 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
- Tornado: Is there a tornado warning now?
- 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 Waukesha County
What natural disasters is Waukesha County, Wisconsin most at risk from?
Waukesha County, Wisconsin has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 88.9 out of 100, higher than about 88% of US counties, with cold waves, hail and tornadoes scoring highest of its 18 hazards and $138 million a year in expected losses.
How many federal disaster declarations has Waukesha County had?
OpenFEMA lists 17 federal disaster declarations that included Waukesha County since 1969, 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 Waukesha County?
NOAA's Storm Prediction Center recorded 39 tornadoes touching Waukesha County from 1950 to 2025. The deadliest: 27 Apr 1984, F4, 6.5 mi path, 1 killed, 14 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.