Natural hazards · O'Fallon

O'Fallon, IL natural hazards

Most of the natural-hazard damage FEMA expects in O'Fallon comes from inland flooding, and overall the risk is moderate for a U.S. community. Flood insurance has paid 12 claims here since 2000. 3 federal disasters brought FEMA money into town.

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

Expected damage

How exposed is O'Fallon?

Moderate

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in O'Fallon to be higher than in 57% of U.S. communities, mostly from inland flooding and earthquakes.

Inland flooding32%Earthquakes28%Heat waves13%Cold waves12%Tornadoes10%Everything else6%

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

32% of expected damage

Above average · higher than 51% of U.S. places

Recorded about 2 times a year in the area

Earthquakes

28% of expected damage

Well above average · higher than 84% of U.S. places

Heat waves

13% of expected damage

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

Recorded about 15 times a year in the area

Cold waves

12% of expected damage

Well below average · higher than 20% of U.S. places

Recorded about once a year in the area

Tornadoes

10% of expected damage

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

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.

12paid claims since 2000

$417Kpaid to owners

2homes flooded more than once

20002026

Biggest named events

Mid-spring storms: 3 claims, $7K
Hurricane Ike: 2 claims, $87K
Late July Flooding: 1 claim, $7K

Homes that flooded again and again

■ FEMA “severe repetitive loss” (0) ■ flooded 2+ times

of all homes
are insured

No community discount. O'Fallon isn’t in FEMA’s Community Rating System, which cuts flood insurance up to 45% in towns that do extra flood-proofing.

Insurance rates: St. Clair County.

Disasters that hit O'Fallon

3 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. Clair County only

2024

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

4 households applied for aid $3K aid approved

2022

Severe Storm and Flooding

2 households applied for aid

2006

Severe Winter Storm

$212K to the City of O'Fallon for repairs

St. Clair County has had 17 natural disasters declared since 1953, most often floods and severe storms.

Around O'Fallon

O'Fallon and the towns around it

Very lowLowModerateHighVery high

Scott AFBmostly inland floodingHigh

Shilohmostly inland floodingHigh

St. Clairmostly inland floodingHigh

Shiloh Valleymostly inland floodingHigh

Swanseamostly inland floodingHigh

Caseyvillemostly earthquakesHigh

O'Fallonmostly inland floodingModerate

Fairview Heightsmostly earthquakesModerate

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 5 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 $11.8M 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.