Natural hazards · Union

Union, CA natural hazards

Most of the natural-hazard damage FEMA expects in Union comes from earthquakes, and overall the risk is very high for a U.S. community. Flood insurance has paid 19 claims here since 1995. 3 federal disasters brought FEMA money into town.

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

Expected damage

How exposed is Union?

Very high

vs. U.S. communities

FEMA expects yearly storm and flood damage to homes and buildings in Union to be higher than in 91% of U.S. communities, mostly from earthquakes and inland flooding.

Earthquakes62%Inland flooding35%Everything else4%

By hazard

What Union faces

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

Earthquakes

62% of expected damage

Well above average · higher than 96% of U.S. places

Inland flooding

35% of expected damage

Well above average · higher than 88% of U.S. places

Recorded about 2 times a year in the area

Lower here

Coastal floodingTornadoesHailWinter weatherHeat wavesWildfireLandslidesStrong windLightningDroughtTsunamisVolcanic activity

Not a risk here

HurricanesIce stormsCold wavesAvalanches

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 Union flood?

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

19paid claims since 1995

$499Kpaid to owners

1homes flooded more than once

19952026

Biggest named events

Pineapple Express - Southern: 9 claims, $202K

Homes that flooded again and again

■ FEMA “severe repetitive loss” (1) ■ flooded 2+ times

of homes in flood zones
are insured

of all homes
are insured

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

Insurance rates: Alameda County.

Disasters that hit Union

3 federal disasters brought FEMA money here

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

Brought FEMA money into UnionDeclared for Alameda County only

2023

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

$14K to the City of Union for repairs

2022

Severe Winter Storms, Flooding, Landslides, and Mudslides

32 households applied for aid $25K aid approved $87K to the City of Union for repairs

2017

Severe Winter Storms, Flooding, and Mudslides

$15K to the City of Union for repairs

Alameda County has had 20 natural disasters declared since 1953, most often severe storms and floods.

Around Union

Union and the towns around it

Very lowLowModerateHighVery high

Fremontmostly earthquakesVery high

Haywardmostly earthquakesVery high

Union Citymostly 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. Union covers 16 census tracts, combined by population.

Money that reached townFlood claims are matched to Union’s own flood-insurance community; household aid to the registrant’s city; repair grants to the City of Union. 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 Union total about $59.8M 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.