Brown County, Illinois Natural Disaster Risk
FEMA National Risk Index assessment · IL
Very LowComposite Risk Score
National percentile: 5th
Brown County faces very low composite natural disaster risk (NRI Risk Index score 4.7, 5th national percentile), driven primarily by landslide and heat wave exposure. Expected annual loss across all 18 hazard types is $3M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Brown County is very low, with a National Risk Index score of 4.7 out of 100 — placing it in the 5th national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in landslide (downhill movement of rock, soil, and debris on unstable slopes) at Low risk — $15K in expected annual loss and about 0.30 events per year; heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Low risk — $686K in expected annual loss and about 8.37 events per year; and drought (extended dry periods that stress water supplies and agriculture) at Low risk — $216K in expected annual loss and about 3.88 events per year. Across all hazards, FEMA estimates $3M in expected annual loss for a population of 6K.
Beyond physical exposure, Brown County has a low social vulnerability rating (how susceptible the population is to harm) and a 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: Brown County has received 16 federal disaster declarations since 1973, including 5 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 102 Illinois counties, Brown County ranks #101 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | Low | 0.30 / yr | $15K |
| Heat Wave | Low | 8.37 / yr | $686K |
| Drought | Low | 3.88 / yr | $216K |
| Cold Wave | Low | 4.16 / yr | $922K |
| Earthquake | Very Low | 0.00 / yr | $64K |
| Strong Wind | Low | 4.65 / yr | $249K |
| Hail | Very Low | 3.62 / yr | $87K |
| Tornado | Very Low | 0.23 / yr | $206K |
| Ice Storm | Very Low | 1.60 / yr | $11K |
| Lightning | Very Low | 46.87 / yr | $43K |
| Winter Weather | Very Low | 9.89 / yr | $10K |
| Hurricane | Very Low | 0.01 / yr | $2K |
| Riverine Flood | Very Low | 0.64 / yr | $653K |
| Wildfire | Very Low | 0.00 / yr | $84 |
| 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
Brown County has received 16 federal disaster declarations since 1973, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Flood (5), Severe Storm (4), Snowstorm (3).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| May 2013 | Flood | Severe Storms, Straight-Line Winds, and Flooding |
| March 2011 | Snowstorm | Severe Winter Storm and Snowstorm |
| December 2006 | Snowstorm | Snow |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| May 2003 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| May 2002 | Tornado | Severe Storms, Tornadoes and Flooding |
| January 1999 | Snowstorm | Il-Winter Storm 1/1/99 |
| May 1996 | Severe Storm | Severe Storms and Flooding |
Showing the 10 most recent of 16 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Brown County?
Brown County has a composite FEMA National Risk Index score of 4.7 out of 100, placing it in the Very Low category and the 5th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Brown County?
The three highest-rated hazards are Landslide (Low, $15K EAL), Heat Wave (Low, $686K EAL), Drought (Low, $216K EAL). These account for most of the county's expected annual losses.
How does Brown County compare to other Illinois counties?
Brown County ranks #101 of 102 Illinois counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Brown County had?
FEMA records 16 federal disaster declarations for Brown County since 1973, most often 5 for flood events and 4 for severe storm events. The most recent was Covid-19 Pandemic, declared in March 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. Brown County's $3M EAL is a statistical average, not a guarantee for any specific year or address.