On FEMA’s figures, Union City faces more hazard damage per building than 95% of U.S. towns, mostly from earthquakes
On FEMA’s National Risk Index, Union City gets a D for hazard risk: higher expected damage per building than 95% of U.S. towns, #541 of 847 in California. Most of that expected damage is earthquakes (55%), then river and rain flooding (42%). Flood insurance has paid 19 claims here since 1995.
Graded on FEMA’s expected yearly building damage per dollar of building value (NRI v1.20, December 2025), weighted by where residents live; flood claims are shown, not graded. How hazard risk is graded
What Union City faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
Earthquakes
River and rain flooding
Shares are of FEMA’s expected building damage, the measure the grade uses; ranks compare each hazard’s building-damage rate with all 85,154 U.S. census tracts. In FEMA’s terms, river and rain flooding is FEMA’s “Inland Flooding” (rivers and streams overflowing their banks, or rain overwhelming drainage). FEMA defines coastal flooding as high or rising tides and storm surge, so surge damage is counted there. Drought isn’t listed: FEMA counts its losses in crops only.
What’s behind Union City’s grade
Earthquakes are 55% of the building damage FEMA expects in Union City, and Union City’s rate of earthquakes damage is in the top 4% of U.S. census tracts. Coastal flooding adds 2%, at a rate in the top 3% of U.S. census tracts.
D #541 of 847 in California; higher expected damage per building than 95% of U.S. towns (21,298).
Union City’s residents live in 18 census tracts; FEMA’s figures are combined by where they live.
The typical California town has higher expected damage than 92% of U.S. towns; within the state, Union City has more expected damage per building than 64% of California towns.
In dollars, FEMA expects about $60.5M a year in losses across Union City: $49.2M to buildings, the rest to people and crops.
Does Union City flood? Sometimes: 19 flood claims since 1995
Every paid claim on a federal flood insurance policy in Union City, from FEMA’s records: 0.9 per 1,000 homes, fewer than 81% of the 13,809 U.S. towns with a flood insurance record.
- The Pineapple Express - Southern9 claims · $202K
Union City 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.3 federal disasters brought FEMA money to Union City
Disasters that paid out in Union City itself (aid to households or repair grants to the City of Union City), newest first, with that year’s flood claims.
- 2023Severe Winter Storms, Straight-line Winds, Flooding, Landslides, and Mudslides$14K to the City of Union City for repairs
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides32 households applied for aid$25K aid approved$87K to the City of Union City for repairs
- 2017Severe Winter Storms, Flooding, and Mudslides$15K to the City of Union City for repairs
Alameda County has had 20 natural disasters declared by the President since 1953, most often severe storms, then floods. Not counted: the 2005 Hurricane Katrina evacuee emergency, which covered counties that took in evacuees.
Old photos of Union City after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Union City archive →Union City and its neighbors
Union City has the lowest expected damage per building of the 3 graded towns here. Tap a town to see its hazards.
Hazard risk = FEMA’s expected yearly building damage per dollar of building value, vs. the 21,298 U.S. towns we grade; the map is shaded by fifths of the same scale. Flood claims = paid federal flood insurance claims on record.
Get ready for what Union City faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- Turn around at flooded roads: a foot of moving water can carry off a car.
- Flood insurance usually takes 30 days to start, so buy it before the forecast.
- Keep papers and medicines up high, in a grab-and-go bag.
- Look up the address on FEMA’s flood map.
- Ask the seller or landlord whether it has ever flooded, and what flood insurance costs there.
- Get a flood insurance quote early: policies usually start 30 days after you buy.
Know where neighbors sign up for alerts? Add it to the Handbook so everyone has it.
Questions about natural hazards in Union City
Is Union City at risk for natural disasters?
On FEMA’s National Risk Index, Union City has higher expected damage per building than 95% of U.S. towns: D for hazard risk, #541 of 847 in California. Most of the expected damage is earthquakes (55%) and river and rain flooding (42%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Union City flood?
Flood insurance has paid 19 claims in Union City since 1995, $499K in all, or 0.9 per 1,000 homes, fewer than 81% of U.S. towns with a flood insurance record. 1 properties have flooded more than once. The most claims came from Pineapple Express - Southern (9).
Is Union City in a flood zone?
Flood zones are drawn street by street, so the answer depends on the address: look it up on FEMA’s flood map. In Alameda County, 36% of homes in mapped flood zones carry federal flood insurance, and 0.8% of all homes do.
How much is flood insurance in Union City?
FEMA’s Community Rating System list shows no discount for Union City’s flood program. Premiums depend on the building; policies usually start 30 days after you buy, so get a quote early.
What was the biggest storm in Union City?
By FEMA money that reached Union City, Severe Winter Storms, Flooding, Landslides, and Mudslides (2022): 32 households applied for aid, $25K approved, and $87K to the City of Union City for repairs. By flood claims, Pineapple Express - Southern: 9 paid, $202K.
Is Union City at risk from earthquakes?
It is the largest share of the building damage FEMA expects here (55%), and Union City’s rate for it is in the top 4% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Union City.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Union City’s residents lived in the 2020 census; 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. Homes: Census ACS 2020–24. Preparedness tips: Ready.gov. FEMA’s model is an average of expected damage, not a forecast. How hazard risk is graded.