St. Clair County, Michigan Natural Disaster Risk
FEMA National Risk Index assessment · MI
MediumComposite Risk Score
National percentile: 82th
St. Clair County faces medium composite natural disaster risk (NRI Risk Index score 82.0, 82th national percentile), driven primarily by cold wave and tornado exposure. Expected annual loss across all 18 hazard types is $49M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in St. Clair County is medium, with a National Risk Index score of 82.0 out of 100 — placing it in the 82nd national percentile and near the national midpoint 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 High risk — $10M in expected annual loss and about 3.00 events per year; tornado (violently rotating columns of air capable of catastrophic local damage) at Medium risk — $6M in expected annual loss and about 0.21 events per year; and ice storm (freezing rain that coats surfaces in heavy, damaging ice) at High risk — $705K in expected annual loss and about 1.90 events per year. Across all hazards, FEMA estimates $49M in expected annual loss for a population of 160K.
Beyond physical exposure, St. Clair County has a 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: St. Clair County has received 12 federal disaster declarations since 1972, including 3 for severe storm events and 3 for flood events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 83 Michigan counties, St. Clair County ranks #11 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Cold Wave | High | 3.00 / yr | $10M |
| Tornado | Medium | 0.21 / yr | $6M |
| Ice Storm | High | 1.90 / yr | $705K |
| Riverine Flood | Medium | 1.04 / yr | $29M |
| Strong Wind | High | 3.52 / yr | $2M |
| Heat Wave | Low | 2.37 / yr | $733K |
| Winter Weather | Low | 12.89 / yr | $88K |
| Earthquake | Very Low | 0.00 / yr | $305K |
| Hail | Low | 1.66 / yr | $256K |
| Coastal Flood | Low | 0.01 / yr | $57K |
| Lightning | Low | 32.26 / yr | $199K |
| Landslide | Very Low | 0.10 / yr | $589 |
| Hurricane | Very Low | 0.02 / yr | $24K |
| Wildfire | Very Low | 0.00 / yr | $19K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Drought | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
St. Clair County has received 12 federal disaster declarations since 1972, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Severe Storm (3), Flood (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| June 2004 | Severe Storm | Severe Storms, Tornadoes, and Flooding |
| September 2003 | Other | Power Outage |
| January 2001 | Snowstorm | Snow |
| July 1996 | Severe Storm | Severe Storms and Flooding |
| January 1978 | Snowstorm | Blizzards & Snowstorms |
| March 1976 | Severe Storm | Severe Storms, Tornadoes, Icing & Flooding |
| April 1975 | Flood | Severe Storms, High Winds & Flooding |
Showing the 10 most recent of 12 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for St. Clair County?
St. Clair County has a composite FEMA National Risk Index score of 82.0 out of 100, placing it in the Medium category and the 82th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in St. Clair County?
The three highest-rated hazards are Cold Wave (High, $10M EAL), Tornado (Medium, $6M EAL), Ice Storm (High, $705K EAL). These account for most of the county's expected annual losses.
How does St. Clair County compare to other Michigan counties?
St. Clair County ranks #11 of 83 Michigan counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has St. Clair County had?
FEMA records 12 federal disaster declarations for St. Clair County since 1972, most often 3 for severe storm events and 3 for flood 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. St. Clair County's $49M EAL is a statistical average, not a guarantee for any specific year or address.