Ozaukee County, Wisconsin Natural Disaster Risk
FEMA National Risk Index assessment · WI
LowComposite Risk Score
National percentile: 50th
Ozaukee County faces low composite natural disaster risk (NRI Risk Index score 50.3, 50th national percentile), driven primarily by cold wave and hail exposure. Expected annual loss across all 18 hazard types is $33M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Ozaukee County carries a low composite natural disaster risk, with a National Risk Index score of 50.3 out of 100 — placing it in the 50th national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $9M in expected annual loss and about 5.26 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Low risk — $1M in expected annual loss and about 2.18 events per year; and tornado (violently rotating columns of air capable of catastrophic local damage) at Low risk — $3M in expected annual loss and about 0.37 events per year. Across all hazards, FEMA estimates $33M in expected annual loss for a population of 91K.
Beyond physical exposure, Ozaukee 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.
History supports the rating: Ozaukee County has received 13 federal disaster declarations since 1965, including 4 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic (biological), declared in April 2020.
Among 72 Wisconsin counties, Ozaukee County ranks #47 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | Medium | 5.26 / yr | $9M |
| Hail | Low | 2.18 / yr | $1M |
| Tornado | Low | 0.37 / yr | $3M |
| Riverine Flood | Low | 1.04 / yr | $17M |
| Heat Wave | Low | 2.21 / yr | $994K |
| Winter Weather | Low | 15.68 / yr | $107K |
| Lightning | Low | 32.08 / yr | $344K |
| Coastal Flood | Very Low | 0.01 / yr | $11K |
| Strong Wind | Low | 2.44 / yr | $608K |
| Earthquake | Very Low | 0.00 / yr | $103K |
| Drought | Very Low | 0.34 / yr | $12K |
| Ice Storm | Very Low | 0.33 / yr | $34K |
| Wildfire | Very Low | 0.00 / yr | $15K |
| Landslide | Very Low | 0.04 / yr | $135 |
| Hurricane | Very Low | 0.01 / yr | $2K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Ozaukee County has received 13 federal disaster declarations since 1965, most recently Covid-19 Pandemic in April 2020. Most frequent causes: Flood (4), Severe Storm (4), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| October 2018 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, Flooding, and Landslides |
| June 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| June 2004 | Severe Storm | Severe Storms and Flooding |
| January 2001 | Snowstorm | Snow |
| July 1997 | Severe Storm | Severe Storms and Flooding |
| August 1991 | Severe Storm | Severe Storms & Hail |
| October 1986 | Flood | Severe Storms & Flooding |
Showing the 10 most recent of 13 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Ozaukee County?
Ozaukee County has a composite FEMA National Risk Index score of 50.3 out of 100, placing it in the Low category and the 50th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Ozaukee County?
The three highest-rated hazards are Cold Wave (Medium, $9M EAL), Hail (Low, $1M EAL), Tornado (Low, $3M EAL). These account for most of the county's expected annual losses.
How does Ozaukee County compare to other Wisconsin counties?
Ozaukee County ranks #47 of 72 Wisconsin counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Ozaukee County had?
FEMA records 13 federal disaster declarations for Ozaukee County since 1965, most often 4 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic, declared in April 2020.
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. Ozaukee County's $33M EAL is a statistical average, not a guarantee for any specific year or address.