Natural hazards · Acalanes Ridge

Acalanes Ridge, CA natural hazards

Most of the natural-hazard damage FEMA expects in Acalanes Ridge comes from earthquakes, and overall the risk is very high for a U.S. community.

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

Expected damage

How exposed is Acalanes Ridge?

Very high

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in Acalanes Ridge to be higher than in 89% of U.S. communities, mostly from earthquakes and inland flooding.

Earthquakes56%Inland flooding42%Everything else3%

By hazard

What Acalanes Ridge faces

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

Earthquakes

56% of expected damage

Well above average · higher than 95% of U.S. places

Inland flooding

42% of expected damage

Well above average · higher than 87% of U.S. places

Recorded about once a year in the area

Lower here

TornadoesHailHeat wavesWildfireLandslidesStrong windLightningDroughtVolcanic activity

Not a risk here

Coastal floodingHurricanesIce stormsWinter weatherCold wavesAvalanchesTsunamis

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 Acalanes Ridge flood?

FEMA's records show no paid flood insurance claims in Acalanes Ridge.

of homes in flood zones
are insured

of all homes
are insured

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

Insurance rates: Contra Costa County.

Disasters that hit Acalanes Ridge

Federal disasters declared here

None of the disasters declared for Contra Costa County shows FEMA aid or repair money reaching Acalanes Ridge itself in FEMA’s records.

Brought FEMA money into Acalanes RidgeDeclared for Contra Costa County only

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

Around Acalanes Ridge

Acalanes Ridge and the towns around it

Very lowLowModerateHighVery high

Saranapmostly inland floodingVery high

Lafayettemostly inland floodingVery high

Walnut Creekmostly earthquakesVery high

Acalanes Ridgemostly 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. Acalanes Ridge is smaller than a census tract, so it shares the figures of the tract around its center.

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

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.