Natural hazards · Alto

Alto, CA natural hazards

Most of the natural-hazard damage FEMA expects in Alto comes from inland flooding, 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 Alto?

Very high

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in Alto to be higher than in 83% of U.S. communities, mostly from inland flooding and earthquakes.

Inland flooding48%Earthquakes41%Tsunamis6%Everything else5%

By hazard

What Alto faces

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

Inland flooding

48% of expected damage

Well above average · higher than 81% of U.S. places

Recorded about 2 times a year in the area

Earthquakes

41% of expected damage

Well above average · higher than 90% of U.S. places

Tsunamis

6% of expected damage

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

Lower here

Coastal floodingTornadoesHailWinter weatherHeat wavesWildfireLandslidesStrong windLightningVolcanic activity

Not a risk here

HurricanesIce stormsCold wavesDroughtAvalanches

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 Alto flood?

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

of homes in flood zones
are insured

of all homes
are insured

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

Insurance rates: Marin County.

Disasters that hit Alto

Federal disasters declared here

None of the disasters declared for Marin County shows FEMA aid or repair money reaching Alto itself in FEMA’s records.

Brought FEMA money into AltoDeclared for Marin County only

Marin County has had 22 natural disasters declared since 1953, most often floods and severe storms.

Around Alto

Alto and the towns around it

Very lowLowModerateHighVery high

Altomostly inland floodingVery high

Mill Valleymostly earthquakesVery high

Strawberrymostly earthquakesHigh

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. Alto 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 Alto’s own flood-insurance community; household aid to the registrant’s city; repair grants to Alto. 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.