riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

Waukesha County Disaster Risk

Waukesha County, Wisconsin

FEMA Risk Rating

Relatively Moderate

National Percentile

89th

of 3,144 counties

State Rank

#4

of 72 (1 = highest risk)

Flood Risk

90th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Moderate

Higher than 90% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Relatively Low

Higher than 50% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively High

Higher than 96% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively Low

Higher than 57% of US counties

Hurricane

Tropical cyclone and hurricane risk

Very Low

Higher than 10% of US counties

Risk Overview

About Natural Disaster Risk in Waukesha County, Wisconsin

Waukesha faces above-average risk

Waukesha County scores 88.87 on the composite risk index, placing it in the relatively moderate risk category and 50% above Wisconsin's state average of 59.08. Among Wisconsin counties, Waukesha ranks among the highest-risk communities.

Second-highest risk in Wisconsin

Waukesha ranks near the top of Wisconsin's risk tier, with exposure to multiple high-impact hazards. The county's rapid suburban development in flood-prone areas and high tornado frequency drive its elevated composite score.

Waukesha's risk stands out regionally

Waukesha's composite score of 88.87 significantly exceeds nearby Washington County (68.32) and Walworth County (74.78). It ranks among the riskiest counties in southeastern Wisconsin's urban corridor.

Tornadoes and flooding hit hardest

Tornado risk scores 95.71—the highest in the county and among Wisconsin's most dangerous—while flood risk reaches 89.76, affecting major urban and suburban zones. Earthquake risk (57.44) and wildfire risk (49.68) pose secondary but notable threats.

Comprehensive coverage is critical

Waukesha residents must prioritize comprehensive homeowners insurance with strong wind and tornado protection. Flood insurance is non-negotiable for any property in a mapped flood zone or with flood history; the county's high flood score means many areas face genuine inundation risk.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in Waukesha County

Top Hazards by Exposure

  1. #1
    TornadoPrepare
    96th percentile
  2. #2
    FloodPrepare
    90th percentile
  3. #3
    EarthquakePrepare
    57th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Risk Advisory: Waukesha County

Risk Verdict

With a composite score at the 89th percentile, Waukesha County sits above the national median for natural hazard exposure. Proactive preparedness — not reactive response — is key to managing life in one of the country's higher-risk counties; Waukesha County residents should plan accordingly.

Hazard Breakdown

Tornado risk is Waukesha County's dominant natural hazard, ranked at the 96th percentile nationally under FEMA's National Risk Index. Flood ranks second at the 90th percentile nationally. Additional tracked hazards include earthquake (57th percentile), wildfire (50th percentile), hurricane (10th percentile).

Preparedness Context

At the 96th percentile nationally for tornado risk, Waukesha County households benefit most from a reliable alert system — a NOAA weather radio that activates during overnight hours when residents may not be checking smartphone alerts. Flood is the second hazard driver for Waukesha County at the 90th percentile nationally, meaning households should maintain awareness of both severe-weather and flood-specific warning systems. For Waukesha County households, a pre-decided family shelter plan — who goes where, how children are retrieved from school during a warning, and a neighborhood meet-up point if phones fail — provides real protection that no supply kit alone can replicate.

Regional Context

At 29.8 points above the Wisconsin state average, Waukesha County carries meaningfully higher natural disaster exposure than a typical Wisconsin county.

Is your household prepared for Waukesha County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in Waukesha County, WI?
Waukesha County has a FEMA National Risk Index rating of Relatively Moderate, placing it in the 89th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.
What types of natural hazards affect Waukesha County?
Waukesha County is evaluated for five major natural hazard types: tornado (96th percentile), flooding (90th percentile), earthquake (57th percentile), wildfire (50th percentile), hurricane (10th percentile). The highest-risk hazard is tornado at the 96th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.
How does Waukesha County risk compare to the Wisconsin average?
Waukesha County's composite risk percentile is 89th, compared to the Wisconsin state average of 59th percentile. The state's overall risk rating is Relatively Low. This means Waukesha County faces higher natural disaster risk than the typical county in Wisconsin.
Is Waukesha County at risk for tornado?
Yes, Waukesha County's tornado risk is at the 96th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Waukesha County is at the 90th percentile.
How is natural disaster risk measured?
FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.
Why is Waukesha County higher risk than average?
Waukesha County's composite risk score of 89th percentile is above the Wisconsin state average of 59th percentile. This elevated risk is driven by tornado exposure (96th percentile), along with flooding and earthquake risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.
By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.