Jefferson County, Wisconsin Natural Disaster Risk
FEMA National Risk Index assessment · WI
LowComposite Risk Score
National percentile: 76th
Jefferson County faces low composite natural disaster risk (NRI Risk Index score 75.8, 76th national percentile), driven primarily by hail and tornado exposure. Expected annual loss across all 18 hazard types is $42M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Jefferson County is low, with a National Risk Index score of 75.8 out of 100 — placing it in the 76th 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 hail (ice stones from severe thunderstorms that damage property and crops) at Medium risk — $3M in expected annual loss and about 3.96 events per year; tornado (violently rotating columns of air capable of catastrophic local damage) at Medium risk — $7M in expected annual loss and about 0.43 events per year; and cold wave (prolonged spells of dangerously low temperatures) at Medium risk — $6M in expected annual loss and about 5.47 events per year. Across all hazards, FEMA estimates $42M in expected annual loss for a population of 85K.
Beyond physical exposure, Jefferson 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: Jefferson County has received 14 federal disaster declarations since 1965, including 5 for severe storm events and 3 for flood events. The most recent was Severe Storms, Tornadoes, and Flooding (flood), declared in June 2026.
Among 72 Wisconsin counties, Jefferson County ranks #18 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Hail | Medium | 3.96 / yr | $3M |
| Tornado | Medium | 0.43 / yr | $7M |
| Cold Wave | Medium | 5.47 / yr | $6M |
| Lightning | Medium | 36.91 / yr | $896K |
| Riverine Flood | Medium | 1.57 / yr | $23M |
| Heat Wave | Low | 3.42 / yr | $1M |
| Strong Wind | Medium | 4.55 / yr | $1M |
| Winter Weather | Low | 15.11 / yr | $104K |
| Landslide | Very Low | 0.11 / yr | $3K |
| Ice Storm | Low | 0.60 / yr | $76K |
| Earthquake | Very Low | 0.00 / yr | $225K |
| Wildfire | Very Low | 0.00 / yr | $31K |
| Drought | Low | 1.64 / yr | $64K |
| Hurricane | Very Low | 0.01 / yr | $4K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Jefferson County has received 14 federal disaster declarations since 1965, most recently Severe Storms, Tornadoes, and Flooding in June 2026. Most frequent causes: Severe Storm (5), Flood (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| June 2026 | Flood | Severe Storms, Tornadoes, and Flooding |
| April 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2008 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| March 2008 | Snowstorm | Record Snow and Near Record Snow |
| August 2007 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| June 2004 | Severe Storm | Severe Storms and Flooding |
| July 1993 | Severe Storm | Severe Storms, Tornadoes & Flooding |
| August 1991 | Severe Storm | Severe Storms & Hail |
Showing the 10 most recent of 14 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Jefferson County?
Jefferson County has a composite FEMA National Risk Index score of 75.8 out of 100, placing it in the Low category and the 76th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Jefferson County?
The three highest-rated hazards are Hail (Medium, $3M EAL), Tornado (Medium, $7M EAL), Cold Wave (Medium, $6M EAL). These account for most of the county's expected annual losses.
How does Jefferson County compare to other Wisconsin counties?
Jefferson County ranks #18 of 72 Wisconsin counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Jefferson County had?
FEMA records 14 federal disaster declarations for Jefferson County since 1965, most often 5 for severe storm events and 3 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. Jefferson County's $42M EAL is a statistical average, not a guarantee for any specific year or address.