St. Charles County, Missouri Natural Disaster Risk
FEMA National Risk Index assessment · MO
MediumComposite Risk Score
National percentile: 93th
St. Charles County faces medium composite natural disaster risk (NRI Risk Index score 92.6, 93th national percentile), driven primarily by strong wind and hail exposure. Expected annual loss across all 18 hazard types is $215M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in St. Charles County is medium, with a National Risk Index score of 92.6 out of 100 — placing it in the 93rd 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.
Most of St. Charles County's expected losses come from strong wind (damaging straight-line winds outside of tornadoes and hurricanes) at Very High risk — $10M in expected annual loss and about 5.89 events per year; hail (ice stones from severe thunderstorms that damage property and crops) at High risk — $9M in expected annual loss and about 5.29 events per year; and tornado (violently rotating columns of air capable of catastrophic local damage) at High risk — $28M in expected annual loss and about 0.46 events per year. Across all hazards, FEMA estimates $215M in expected annual loss for a population of 405K.
Beyond physical exposure, St. Charles 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.
The federal record bears this out: St. Charles County has received 28 federal disaster declarations since 1965, including 11 for severe storm events and 9 for flood events. The most recent was Severe Storms and Flooding (flood), declared in August 2022.
Among 115 Missouri counties, St. Charles County ranks #4 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Strong Wind | Very High | 5.89 / yr | $10M |
| Hail | High | 5.29 / yr | $9M |
| Tornado | High | 0.46 / yr | $28M |
| Heat Wave | Medium | 14.74 / yr | $12M |
| Earthquake | Medium | 0.00 / yr | $22M |
| Riverine Flood | High | 2.07 / yr | $116M |
| Landslide | Medium | 0.44 / yr | $144K |
| Cold Wave | High | 1.74 / yr | $15M |
| Lightning | High | 50.98 / yr | $2M |
| Winter Weather | High | 8.79 / yr | $658K |
| Ice Storm | Medium | 1.29 / yr | $416K |
| Wildfire | Very Low | 0.00 / yr | $135K |
| Drought | Low | 1.92 / yr | $56K |
| Hurricane | Very Low | 0.01 / yr | $13K |
| 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. Charles County has received 28 federal disaster declarations since 1965, most recently Severe Storms and Flooding in August 2022. Most frequent causes: Severe Storm (11), Flood (9), Severe Ice Storm (3).
| Declared | Type | Disaster |
|---|---|---|
| August 2022 | Flood | Severe Storms and Flooding |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2019 | Severe Storm | Severe Storms, Tornadoes, 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 |
| February 2011 | Severe Storm | Severe Winter Storm |
| January 2009 | Severe Ice Storm | Severe Winter Storm |
Showing the 10 most recent of 28 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for St. Charles County?
St. Charles County has a composite FEMA National Risk Index score of 92.6 out of 100, placing it in the Medium category and the 93th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in St. Charles County?
The three highest-rated hazards are Strong Wind (Very High, $10M EAL), Hail (High, $9M EAL), Tornado (High, $28M EAL). These account for most of the county's expected annual losses.
How does St. Charles County compare to other Missouri counties?
St. Charles County ranks #4 of 115 Missouri counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has St. Charles County had?
FEMA records 28 federal disaster declarations for St. Charles County since 1965, most often 11 for severe storm events and 9 for flood events. The most recent was Severe Storms and Flooding, declared in August 2022.
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. Charles County's $215M EAL is a statistical average, not a guarantee for any specific year or address.