Natural hazards · Ontario

Ontario, CA natural hazards

Most of the natural-hazard damage FEMA expects in Ontario comes from inland flooding, and overall the risk is very high for a U.S. community. Flood insurance has paid 10 claims here since 1980. 6 federal disasters brought FEMA money into town.

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

Expected damage

How exposed is Ontario?

Very high

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in Ontario to be higher than in 98% of U.S. communities, mostly from inland flooding and earthquakes.

Inland flooding56%Earthquakes41%Everything else4%

By hazard

What Ontario faces

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

Inland flooding

56% of expected damage

Well above average · among the top 1% of U.S. places

Recorded about 13 times a year in the area

Earthquakes

41% of expected damage

Well above average · higher than 94% of U.S. places

Lower here

TornadoesHailWinter weatherHeat wavesWildfireLandslidesStrong windLightningDrought

Not a risk here

Coastal floodingHurricanesIce stormsCold wavesAvalanchesTsunamisVolcanic 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 Ontario flood?

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

10paid claims since 1980

$74Kpaid to owners

1homes flooded more than once

19802026

Homes that flooded again and again

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

of homes in flood zones
are insured

of all homes
are insured

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

Insurance rates: San Bernardino County.

Disasters that hit Ontario

6 federal disasters brought FEMA money here

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

Brought FEMA money into OntarioDeclared for San Bernardino County only

2023

Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides

40 households applied for aid $30K aid approved

2020

Wildfires

30 households applied for aid $10K aid approved

2010

Severe Winter Storms, Flooding, and Debris and Mud Flows

$63K to the City of Ontario for repairs

2007

Wildfires, Flooding, Mud Flows, and Debris Flows

11 households applied for aid $193K to the City of Ontario for repairs

2004

Severe Storms, Flooding, Debris Flows, and Mudslides

22 households applied for aid $11K aid approved $384K to the City of Ontario for repairs

2003

Wildfires, Flooding, Mudflow and Debris Flow Directly Related T

92 households applied for aid $14K aid approved

San Bernardino County has had 56 natural disasters declared since 1953, most often fires and floods.

Around Ontario

Ontario and the towns around it

Very lowLowModerateHighVery high

Eastvalemostly inland floodingVery high

Chinomostly inland floodingVery high

Ontariomostly inland floodingVery high

Rancho Cucamongamostly inland floodingVery high

Uplandmostly inland floodingVery high

Fontanamostly earthquakesVery high

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. Ontario covers 35 census tracts, combined by population.

Money that reached townFlood claims are matched to Ontario’s own flood-insurance community; household aid to the registrant’s city; repair grants to the City of Ontario. 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 Ontario total about $200M 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.