San Joaquin County, California: Natural Disaster Risk and History
San Joaquin County, California has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 98.6 out of 100, higher than about 98% of US counties, with drought, earthquakes and inland (river and flash) flooding scoring highest of its 18 hazards and $422 million a year in expected losses.
OpenFEMA lists 23 federal disaster declarations that included San Joaquin County since 1964, not counting 2 for COVID-19; the latest is DR-4699-CA (Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, declared 3 April 2023). NOAA's Storm Prediction Center recorded 19 tornadoes touching San Joaquin County from 1950 to 2025.
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Population 778,512 Buildings worth $157 billion Area 1,441 sq mi Risk rank in California 17 of 58 FIPS 06077
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Drought | Very High | 99.9 | $83 million | about 69 a year | 2,037 |
| Earthquake | Relatively High | 99.3 | $184 million | about once every 9.3 years | — |
| Inland flooding | Relatively High | 97.7 | $138 million | about 1.1 a year | 31 |
| Heat wave | Relatively High | 97.4 | $11 million | about 7 a year | 79 |
| Lightning | Relatively High | 93.4 | $1.5 million | about 7.7 a year | 86,124 strikes |
| Wildfire | Relatively Moderate | 92.0 | $1.9 million | about once every 317 years | — |
| Volcanic activity | Very Low | 79.8 | $515 | rarer than once in 1,000 years | 2 |
| Landslide | Very Low | 62.0 | $3,006 | about 7.4 a year | — |
| Hail | Relatively Low | 54.7 | $316,186 | about once every 14 years | 2.7 |
| Tornado | Relatively Low | 49.0 | $1.2 million | about once every 5.5 years | 10 |
| Winter weather | Relatively Low | 42.4 | $48,782 | about once every 5.1 years | 3.7 |
| Strong wind | Relatively Low | 38.0 | $383,826 | about once every 21 years | 2 |
| Avalanche | Very Low | 2.2 | — | about once every 100 years | 0 |
| Cold wave | No Rating | 0.0 | — | — | 0 |
| Coastal flooding | Not Applicable | — | — | — | — |
| Hurricane | Not Applicable | — | — | — | — |
| Ice storm | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 23
Most common: Flood 10, Severe Storm 6, Coastal Storm 2, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 2 | Flood ×2 |
| 1970s | 1 | Drought |
| 1980s | 7 | Flood ×4, Coastal Storm ×2, Earthquake |
| 1990s | 4 | Severe Storm ×3, Freezing |
| 2000s | 4 | Severe Storm ×2, Hurricane, Dam/Levee Break |
| 2010s | 1 | Flood |
| 2020s | 4 | Flood ×3, Severe Storm |
The last 10
Widest declarations that included San Joaquin County
- Hurricane Katrina Evacuation (2005, EM-3248-CA): 58 California counties designated.
- Severe Winter Storms, Flooding Landslides, Mud Flow (1995, DR-1046-CA): 57 California counties designated.
- Severe Storms, Flooding, Mud and Landslides (1997, DR-1155-CA): 48 California counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. California also had 30 statewide declarations with no county list.
Tornado record since 1950 19
| Tornadoes touching the county | 19 |
|---|---|
| Strongest-rated | (E)F1 ×3 |
| Peak month | April (10) |
| Deadliest | — |
| Longest path | 27 Apr 1970, F0, 1.5 mi path |
| Most recent | 21 Apr 2022, unrated |
| Deaths / injuries on those paths | 0 / 0 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 15 | 3 | 0 | 0 | 0 | 0 | 1 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 2 | 3 | 4 | 6 | 2 | 1 | 1 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How San Joaquin County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| San Joaquin County (this page) | — | Relatively High | 98.6 | Drought |
| Stanislaus County | 48 km | Relatively High | 96.9 | Drought |
| Contra Costa County | 57 km | Very High | 99.5 | Earthquake |
| Sacramento County | 58 km | Relatively High | 98.1 | Drought |
| Alameda County | 63 km | Very High | 99.8 | Earthquake |
| Solano County | 69 km | Relatively High | 97.0 | Drought |
Nearest by distance between county centres. Every county in California, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 39.7 |
|---|---|
| Community resilience | Relatively Moderate 47.0 |
| Community risk factor | 1.06 |
| Expected annual loss, all hazards | $422 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for San Joaquin County's main hazards
- Right now: National Weather Service alerts for California · all official warnings on Global Incident Tracker.
- Drought: Drought monitor for California
- Earthquake: Earthquakes today · Earthquake safety guide
- Inland flooding: Flood safety: why shallow water kills · Floods recorded
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about San Joaquin County
What natural disasters is San Joaquin County, California most at risk from?
San Joaquin County, California has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 98.6 out of 100, higher than about 98% of US counties, with drought, earthquakes and inland (river and flash) flooding scoring highest of its 18 hazards and $422 million a year in expected losses.
How many federal disaster declarations has San Joaquin County had?
OpenFEMA lists 23 federal disaster declarations that included San Joaquin County since 1964, not counting 2 for COVID-19; the latest is DR-4699-CA (Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides, declared 3 April 2023). Another 30 California declarations were made statewide without a county list.
How many tornadoes have hit San Joaquin County?
NOAA's Storm Prediction Center recorded 19 tornadoes touching San Joaquin County from 1950 to 2025.
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.