Natural hazards · O'Fallon

O'Fallon, MO natural hazards

Most of the natural-hazard damage FEMA expects in O'Fallon comes from inland flooding, and overall the risk is high for a U.S. community. Flood insurance has paid 45 claims here since 1978. 5 federal disasters brought FEMA money into town.

FEMA National Risk Index, December 2025 · OpenFEMA claims, aid & declarations

Expected damage

How exposed is O'Fallon?

High

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in O'Fallon to be higher than in 70% of U.S. communities, mostly from inland flooding.

Inland flooding55%Tornadoes13%Earthquakes8%Cold waves7%Heat waves6%Everything else11%

By hazard

What O'Fallon faces

Each hazard’s share of the damage FEMA expects here, and how that compares with the rest of the country.

Inland flooding

55% of expected damage

Well above average · higher than 82% of U.S. places

Recorded about 2 times a year in the area

Tornadoes

13% of expected damage

Well above average · higher than 80% of U.S. places

Earthquakes

8% of expected damage

Well above average · higher than 78% of U.S. places

Cold waves

7% of expected damage

Well below average · higher than 17% of U.S. places

Recorded about 2 times a year in the area

Heat waves

6% of expected damage

Above average · higher than 73% of U.S. places

Recorded about 15 times a year in the area

Lower here

HurricanesHailIce stormsWinter weatherWildfireLandslidesStrong windLightningDrought

Not a risk here

Coastal floodingAvalanchesTsunamisVolcanic activity

Flood risk changes street by street. Check a specific address on FEMA’s flood map, and ask about flood insurance before you buy.

Flood insurance claims

Does O'Fallon flood?

Every paid claim on a federal flood insurance policy in O'Fallon, from FEMA’s records.

45paid claims since 1978

$1.2Mpaid to owners

4homes flooded more than once

19782026

Biggest named events

Midwest Flooding: 8 claims, $498K
Hurricane Ike: 4 claims, $117K
Late July Flooding: 2 claims, $117K

Homes that flooded again and again

■ FEMA “severe repetitive loss” (2) ■ flooded 2+ times

of homes in flood zones
are insured

of all homes
are insured

🏷️ 05% off flood insurance. O'Fallon is in FEMA’s Community Rating System (class 9) for its flood-proofing work.

Insurance rates: St. Charles County.

What’s been done with FEMA grants

7flood-prone properties bought out and cleared

Disasters that hit O'Fallon

5 federal disasters brought FEMA money here

Disasters the President declared that paid out in O'Fallon itself: aid to households, or repair grants to the City of O'Fallon.

Brought FEMA money into O'FallonDeclared for St. Charles County only

2022

Severe Storms and Flooding

2 households applied for aid $300 aid approved $138K to the City of O'Fallon for repairs

2019

Severe Storms, Tornadoes, and Flooding

$40K to the City of O'Fallon for repairs

2015

Severe Storms, Tornadoes, Straight-Line Winds, and Flooding

2 households applied for aid $138K to the City of O'Fallon for repairs

2008

Severe Storms and Flooding

$2K to the City of O'Fallon for repairs

2007

Severe Winter Storms and Flooding

$82K to the City of O'Fallon for repairs

St. Charles County has had 23 natural disasters declared since 1953, most often severe storms and floods.

Around O'Fallon

O'Fallon and the towns around it

Very lowLowModerateHighVery high

St. Paulmostly inland floodingVery high

Cottlevillemostly inland floodingVery high

Dardenne Prairiemostly inland floodingVery high

O'Fallonmostly inland floodingHigh

St. Petersmostly inland floodingHigh

Wentzvillemostly inland floodingModerate

Weldon Springmostly inland floodingModerate

Lake St. Louismostly inland floodingModerate

Josephvillemostly inland floodingModerate

About these numbers

How to read this page

An average, not a forecastFEMA’s National Risk Index estimates the damage 18 kinds of natural hazards cause in a typical year, from decades of records and models. A quiet decade can follow a bad year.

Compared by rate“Higher than N%” compares yearly damage as a share of what’s here, so a big city isn’t rated riskier just for having more buildings. O'Fallon covers 16 census tracts, combined by population.

Money that reached townFlood claims are matched to O'Fallon’s own flood-insurance community; household aid to the registrant’s city; repair grants to the City of O'Fallon. FEMA’s model follows property values, so a place that recently lost many homes can rate lower than it feels.

FEMA’s expected losses across O'Fallon total about $40.1M a year, counting buildings, people and crops.

Sources: FEMA National Risk Index (December 2025); OpenFEMA: NFIP redacted claims, multiple-loss properties, community status book and residential penetration rates, housing assistance (owners and renters), public assistance funded projects, hazard mitigation properties and disaster declarations. Census tracts: U.S. Census Bureau.