O'Fallon, Missouri Flood Zones
Last updated: March 2026
O'Fallon faces flooding from Dardenne Creek in St. Charles County. Heavy rainfall events cause the creek to overflow and threaten properties in this growing suburban community.
St. Charles County has recorded 9,993 NFIP flood insurance claims since 1978, totaling $151.8M in payouts. Explore the full NFIP claims data by state and county to see how this area compares nationally.
FEMA Region
Region 7
NFIP Policies
1,577
St. Charles County
Avg. Premium
$1,425/yr
St. Charles County
FEMA Flood Risk Profile: St. Charles County
Based on FEMA's National Risk Index, which evaluates flood risk at the county level using historical loss data, exposure, and vulnerability.
Inland Flood Risk
Relatively HighEst. annual loss: $115.9M
Hurricane Risk
Very LowEst. annual loss: $13K
Source: FEMA National Risk Index, county-level assessment. Individual property risk may vary.
Federal Flood Disaster History: St. Charles County
St. Charles County has been included in 10 federal flood-related disaster declarations.
...and 2 earlier declarations since 1982.
These declarations affected communities across St. Charles County, including O'Fallon.
Source: OpenFEMA Disaster Declarations Summaries API. Data sourced February 2026.
NFIP Flood Insurance Claims: St. Charles County
Properties in St. Charles County have filed 9,993 NFIP flood insurance claims totaling $151.8M in payouts since 1978. The average claim payout is $15K.
Highest-Claim Years
1993
2,393 claims - $60.5M
1986
1,083 claims - $8.6M
1983
890 claims - $4.2M
Claims by Flood Zone
Source: OpenFEMA NFIP Claims API. Data sourced March 2026. See national claims data.
Flood Insurance Coverage: St. Charles County
An estimated 1.0% of households in St. Charles County carry NFIP flood insurance. This county has elevated flood risk but very low insurance coverage, indicating a significant protection gap.
Penetration Rate
1.0%
Claims Ratio
1 in 1
policies have filed a claim
Avg. Claim Payout
$15,188
Derived from FEMA NRI population data and OpenFEMA NFIP policy/claims records.
Repetitive Loss Properties: St. Charles County
St. Charles County has 823 properties with multiple flood losses, including 212 severe repetitive loss properties. 172 properties have been mitigated.
Multiple Loss
823
Severe Rep. Loss
212
Mitigated
172
By Flood Zone
Source: OpenFEMA NFIP Multiple Loss Properties. Data sourced March 2026.
Recorded Flood Events: ST. CHARLES County
NOAA has recorded 51 flood events in ST. CHARLES County since 1996, causing $26.3M in damage and 2 deaths.
Costliest Events
Events by Type
Source: NOAA Storm Events Database, 1996-2026. Data sourced March 2026.
Flood Mitigation: St. Charles County
FEMA has funded mitigation for 1,470 properties in St. Charles County, investing $1.6M in flood risk reduction.
By Action Type
Source: OpenFEMA Hazard Mitigation Assistance. Data sourced March 2026.
What Your Flood Zone Means in O'Fallon
O'Fallon faces flood risk primarily from river and stream overflow during heavy rainfall, snowmelt, or upstream dam releases. When rivers exceed their banks, floodwaters spread across low-lying areas mapped in AE and A zones. The most common FEMA flood zone designations in O'Fallon are Zone AE, Zone X. FEMA's National Risk Index estimates the county's annual expected loss from inland flooding at over $115.9M.
Riverine flood risk in O'Fallon is driven by the proximity and elevation of properties relative to nearby waterways. Properties closer to rivers with lower ground elevations typically face higher flood insurance premiums under FEMA's Risk Rating 2.0. If your property is in a Special Flood Hazard Area (SFHA) and you have a federally regulated or government-backed mortgage, federal law generally requires your lender to ensure you carry flood insurance.
River flood maps can change when FEMA conducts new Flood Insurance Studies or when development alters drainage patterns. Letters of Map Amendment (LOMA) can remove individual properties if the natural ground elevation was always above the Base Flood Elevation and the property was inadvertently mapped in the SFHA. Use our free lookup tool to check the current flood zone for any O'Fallon address.
Flood Insurance Discount: O'Fallon
O'Fallon participates in FEMA's Community Rating System (CRS), a voluntary program that rewards communities for flood mitigation efforts beyond minimum NFIP requirements. Residents in the Special Flood Hazard Area may qualify for reduced flood insurance premiums.
CRS Class
Class 9
SFHA Premium Discount
5% off
CRS classes range from 1 (best) to 10 (no discount). O'Fallon's Class 9 rating means NFIP policyholders in the SFHA can receive up to a 5% discount on their flood insurance premiums. Properties outside the SFHA may receive a 5% discount.
Source: FEMA Community Rating System, October 2025. Discounts apply to NFIP policies only.
O'Fallon, MO Flood Zone FAQ
What flood zones are in O'Fallon, MO?
The most common FEMA flood zones in O'Fallon are Zone AE, Zone X. Properties in these high-risk zones (SFHA) may require flood insurance with a federally regulated or government-backed mortgage.
Is flood insurance required in O'Fallon?
If your O'Fallon property is in a Special Flood Hazard Area (SFHA) and you have a federally regulated or government-backed mortgage, federal law generally requires your lender to ensure you carry flood insurance. Properties in Zone X are not federally required to carry flood insurance, though coverage is still recommended since over 40% of all NFIP flood claims come from Zone X properties.
How do I check my flood zone in O'Fallon?
Enter your O'Fallon address in the search tool above for an instant flood zone determination. Results include your FEMA flood zone, SFHA status, base flood elevation (if available), and FIRM panel information, pulled directly from FEMA's National Flood Hazard Layer.
Does O'Fallon offer flood insurance discounts?
Yes. O'Fallon participates in FEMA's Community Rating System (CRS) with a Class 9 rating, qualifying residents in the Special Flood Hazard Area for up to a 5% discount on NFIP flood insurance premiums. Properties outside the SFHA may receive a 5% discount.
Has O'Fallon experienced major flooding events?
St. Charles County, where O'Fallon is located, has been part of 10 federal disaster declarations for flooding, hurricanes, or severe storms. The most recent was Severe Storms and Flooding in 2022. Federal disaster declarations are issued when flooding overwhelms local resources and triggers FEMA assistance programs.
How many flood insurance claims have been filed in O'Fallon?
St. Charles County has recorded 9,993 NFIP flood insurance claims totaling $151.8M in payouts since 1978. The year with the most claims was 1993, with 2,393 claims and $60.5M in payouts. These figures cover all NFIP claims in the county, including O'Fallon.
How many flood insurance policies are active in O'Fallon?
St. Charles County currently has 1,577 active NFIP flood insurance policies with an average annual premium of $1,425. The most policies are in Zone AE (1,145 policies). These figures cover all active NFIP policies in the county.
How many O'Fallon properties have flooded repeatedly?
St. Charles County has 823 properties with multiple flood losses on record, including 212 severe repetitive loss properties. These are properties that have experienced four or more NFIP claims of $5,000+ or two claims exceeding the building value.
Can my O'Fallon property be removed from a high-risk flood zone?
Yes, if your property's natural ground elevation is above the Base Flood Elevation and FEMA inadvertently mapped it in a high-risk zone, you can apply for a Letter of Map Amendment (LOMA). A successful LOMA removes the property from the Special Flood Hazard Area, generally eliminating the federal mandatory flood insurance requirement. You will need an elevation certificate from a licensed surveyor. If a property was raised above the BFE with fill material, the process is a LOMR-F rather than a LOMA.
What is Base Flood Elevation in O'Fallon?
Base Flood Elevation (BFE) is the predicted height of floodwaters during a 1% annual chance (100-year) flood, shown on FEMA maps as an elevation number in feet above sea level. In O'Fallon's Zone AE areas, BFE lines appear on the FIRM as wavy contours labeled with elevation values. Properties with a lowest floor at or above the BFE typically qualify for significantly lower NFIP flood insurance premiums.
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Disclaimer: Flood risk data on this page is sourced from FEMA datasets including the National Risk Index, NFIP claims and policy records, disaster declarations, and the Community Rating System. These datasets were last extracted on March 2026 and may not reflect the most recent changes. This page is for informational purposes only and is not a certified flood zone determination. Always verify current flood zone status through FEMA or a licensed determination provider before making property, insurance, or lending decisions.