Cook County, Illinois Natural Disaster Risk
FEMA National Risk Index assessment · IL
Very HighComposite Risk Score
National percentile: 100th
Cook County faces very high composite natural disaster risk (NRI Risk Index score 100.0, 100th national percentile), driven primarily by cold wave and tornado exposure. Expected annual loss across all 18 hazard types is $2.42B.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Cook County carries a very high composite natural disaster risk, with a National Risk Index score of 100.0 out of 100 — placing it in the 100th national percentile and among the most at-risk counties in the United States. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
The county's risk is driven primarily by cold wave (prolonged spells of dangerously low temperatures) at Very High risk — $700M in expected annual loss and about 4.25 events per year; tornado (violently rotating columns of air capable of catastrophic local damage) at Very High risk — $345M in expected annual loss and about 1.04 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Very High risk — $4M in expected annual loss and about 14.60 events per year. Across all hazards, FEMA estimates $2.42B in expected annual loss for a population of 5.27M.
Beyond physical exposure, Cook County has a high 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). Higher vulnerability is partly offset by strong community resilience and recovery capacity.
The federal record bears this out: Cook County has received 24 federal disaster declarations since 1967, including 8 for flood events and 8 for severe storm events. The most recent was Severe Storms, Tornadoes, Straight-Line Winds, and Floodng (flood), declared in September 2024.
Among 102 Illinois counties, Cook County ranks #1 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | Very High | 4.25 / yr | $700M |
| Tornado | Very High | 1.04 / yr | $345M |
| Winter Weather | Very High | 14.60 / yr | $4M |
| Riverine Flood | Very High | 5.89 / yr | $1.10B |
| Heat Wave | Very High | 2.90 / yr | $193M |
| Strong Wind | Very High | 5.70 / yr | $12M |
| Hail | High | 3.95 / yr | $11M |
| Earthquake | High | 0.00 / yr | $57M |
| Lightning | Very High | 41.54 / yr | $3M |
| Ice Storm | Very High | 0.58 / yr | $2M |
| Landslide | Very Low | 0.14 / yr | $2K |
| Wildfire | Very Low | 0.00 / yr | $56K |
| Hurricane | Very Low | 0.01 / yr | $57K |
| Coastal Flood | Low | 0.01 / yr | $37K |
| Drought | Very Low | 3.86 / yr | $12K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Cook County has received 24 federal disaster declarations since 1967, most recently Severe Storms, Tornadoes, Straight-Line Winds, and Floodng in September 2024. Most frequent causes: Flood (8), Severe Storm (8), Snowstorm (4).
| Declared | Type | Disaster |
|---|---|---|
| September 2024 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Floodng |
| November 2023 | Flood | Severe Storms and Flooding |
| August 2023 | Severe Storm | Severe Storms and Flooding |
| 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 |
| August 2010 | Severe Storm | Severe Storms and Flooding |
| October 2008 | Severe Storm | Severe Storms and Flooding |
| September 2007 | Severe Storm | Severe Storms and Flooding |
Showing the 10 most recent of 24 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Cook County?
Cook County has a composite FEMA National Risk Index score of 100.0 out of 100, placing it in the Very High category and the 100th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Cook County?
The three highest-rated hazards are Cold Wave (Very High, $700M EAL), Tornado (Very High, $345M EAL), Winter Weather (Very High, $4M EAL). These account for most of the county's expected annual losses.
How does Cook County compare to other Illinois counties?
Cook County ranks #1 of 102 Illinois counties for overall natural disaster risk, with a very high rating.
How many federally declared disasters has Cook County had?
FEMA records 24 federal disaster declarations for Cook County since 1967, most often 8 for flood events and 8 for severe storm events. The most recent was Severe Storms, Tornadoes, Straight-Line Winds, and Floodng, declared in September 2024.
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. Cook County's $2.42B EAL is a statistical average, not a guarantee for any specific year or address.