St. Louis County, Missouri Natural Disaster Risk
FEMA National Risk Index assessment · MO
HighComposite Risk Score
National percentile: 99th
St. Louis County faces high composite natural disaster risk (NRI Risk Index score 99.3, 99th national percentile), driven primarily by heat wave and hail exposure. Expected annual loss across all 18 hazard types is $753M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in St. Louis County is high, with a National Risk Index score of 99.3 out of 100 — placing it in the 99th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in heat wave (prolonged periods of extreme heat that threaten health and infrastructure) at Very High risk — $253M in expected annual loss and about 14.84 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at Very High risk — $38M in expected annual loss and about 5.26 events per year; and lightning (electrical discharges from storms that ignite fires and cause casualties) at Very High risk — $5M in expected annual loss and about 52.97 events per year. Across all hazards, FEMA estimates $753M in expected annual loss for a population of 1M.
Beyond physical exposure, St. Louis 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: St. Louis County has received 34 federal disaster declarations since 1973, including 16 for severe storm events and 10 for flood events. The most recent was Severe Storms, Straight-Line Winds, Tornadoes, and Flooding (severe storm), declared in June 2025.
Among 115 Missouri counties, St. Louis County ranks #1 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Heat Wave | Very High | 14.84 / yr | $253M |
| Hail | Very High | 5.26 / yr | $38M |
| Lightning | Very High | 52.97 / yr | $5M |
| Cold Wave | Very High | 1.74 / yr | $41M |
| Riverine Flood | High | 2.79 / yr | $240M |
| Earthquake | High | 0.01 / yr | $141M |
| Ice Storm | Very High | 1.41 / yr | $4M |
| Winter Weather | Very High | 8.74 / yr | $2M |
| Tornado | High | 0.41 / yr | $26M |
| Landslide | Medium | 0.97 / yr | $443K |
| Strong Wind | High | 5.93 / yr | $2M |
| Wildfire | Very Low | 0.00 / yr | $101K |
| Hurricane | Very Low | 0.01 / yr | $48K |
| Drought | Very Low | 1.86 / yr | $20K |
| 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
St. Louis County has received 34 federal disaster declarations since 1973, most recently Severe Storms, Straight-Line Winds, Tornadoes, and Flooding in June 2025. Most frequent causes: Severe Storm (16), Flood (10), Severe Ice Storm (3).
| Declared | Type | Disaster |
|---|---|---|
| June 2025 | Severe Storm | Severe Storms, Straight-Line Winds, Tornadoes, and Flooding |
| May 2025 | Severe Storm | Severe Storms, Straight-Line Winds, Tornadoes, and Wildfires |
| August 2022 | Flood | Severe Storms and Flooding |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| June 2017 | Flood | Severe Storms, Tornadoes, Straight-Line Winds and Flooding |
| January 2016 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| January 2016 | Flood | Severe Storms, Tornadoes, Straight-Line Winds, and Flooding |
| July 2013 | Severe Storm | Severe Storms, Straight-Line Winds, Tornadoes, and Flooding |
| June 2011 | Flood | Flooding |
Showing the 10 most recent of 34 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for St. Louis County?
St. Louis County has a composite FEMA National Risk Index score of 99.3 out of 100, placing it in the High category and the 99th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in St. Louis County?
The three highest-rated hazards are Heat Wave (Very High, $253M EAL), Hail (Very High, $38M EAL), Lightning (Very High, $5M EAL). These account for most of the county's expected annual losses.
How does St. Louis County compare to other Missouri counties?
St. Louis County ranks #1 of 115 Missouri counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has St. Louis County had?
FEMA records 34 federal disaster declarations for St. Louis County since 1973, most often 16 for severe storm events and 10 for flood events. The most recent was Severe Storms, Straight-Line Winds, Tornadoes, and Flooding, declared in June 2025.
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. Louis County's $753M EAL is a statistical average, not a guarantee for any specific year or address.