Photo: Michael "Mike" L. Baird from Morro Bay, USA. · CC BY 2.0On FEMA’s figures, Los Osos faces more hazard damage per building than 63% of U.S. towns, mostly from river and rain flooding
On FEMA’s National Risk Index, Los Osos gets a C+ for hazard risk: higher expected damage per building than 63% of U.S. towns, #91 of 847 in California. Most of that expected damage is river and rain flooding (59%), then earthquakes (33%). Flood insurance has paid 10 claims here since 1992.
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 Los Osos faces
Each hazard’s share of the building damage FEMA expects here, and how its rate compares with the rest of the country.
River and rain flooding
Earthquakes
Wildfire
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 Los Osos’ grade
River and rain flooding is 59% of the building damage FEMA expects in Los Osos, and Los Osos’ rate of river and rain flooding damage is higher than 55% of U.S. census tracts. Wildfire adds 6%, at a rate in the top 8% of U.S. census tracts.
C+ #91 of 847 in California; higher expected damage per building than 63% of U.S. towns (21,298).
Los Osos’ residents live in 4 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, Los Osos has less expected damage per building than 89% of California towns.
In dollars, FEMA expects about $4.4M a year in losses across Los Osos: $4.0M to buildings, the rest to people and crops.
Does Los Osos flood? Sometimes: 10 flood claims since 1992
Every paid claim on a federal flood insurance policy in Los Osos, from FEMA’s records: 1.6 per 1,000 homes, fewer than 68% of the 13,809 U.S. towns with a flood insurance record.
Los Osos 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 Luis Obispo County.3 federal disasters brought FEMA money to Los Osos
Disasters that paid out in Los Osos itself (aid to households or repair grants to Los Osos), newest first, with that year’s flood claims.
- 2023Severe Winter Storms, Straight-line Winds, Flooding, Landslides, and Mudslides9 households applied for aid$10K aid approved
- 2022Severe Winter Storms, Flooding, Landslides, and Mudslides99 households applied for aid$387K aid approved
- 2003Earthquake60 households applied for aid$65K aid approved
San Luis Obispo County has had 23 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.
Also 1 FEMA wildfire suppression grant (Fire Management Assistance, not a disaster declaration) for fires in San Luis Obispo County, 2016–2016.
Old photos of Los Osos after a storm or flood belong in the town’s history. Add one, or share what you remember below.
Add to the Los Osos archive →Get ready for what Los Osos faces
A short kit for the hazards that drive the building damage here, what to check before you buy, and where neighbors get alerts.
- 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.
- Drop, cover and hold on.
- Strap tall furniture and the water heater to the wall.
- Know how to shut off the gas.
- Clear dead leaves and brush within 5 feet of the house.
- Sign up for local alerts and know two ways out.
- Keep N95 masks for smoky days.
- 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 Los Osos
Is Los Osos at risk for natural disasters?
On FEMA’s National Risk Index, Los Osos has higher expected damage per building than 63% of U.S. towns: C+ for hazard risk, #91 of 847 in California. Most of the expected damage is river and rain flooding (59%) and earthquakes (33%). This is FEMA’s model of an average year for today’s buildings, not a forecast.
Does Los Osos flood?
Flood insurance has paid 10 claims in Los Osos since 1992, $66K in all, or 1.6 per 1,000 homes, fewer than 68% of U.S. towns with a flood insurance record.
Is Los Osos 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 San Luis Obispo County, 22% of homes in mapped flood zones carry federal flood insurance, and 1.1% of all homes do.
How much is flood insurance in Los Osos?
FEMA’s Community Rating System list shows no discount for Los Osos’ 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 Los Osos?
By FEMA money that reached Los Osos, Severe Winter Storms, Flooding, Landslides, and Mudslides (2022): 99 households applied for aid, $387K approved.
Is Los Osos at risk from river and rain flooding?
It is the largest share of the building damage FEMA expects here (59%), and Los Osos’ rate for it is higher than 55% of U.S. census tracts.
Storm stories
Memories, warnings and help from neighbors in Los Osos.
Sources: FEMA National Risk Index v1.20 (December 2025), census-tract table, combined by where Los Osos’ 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.