Updated May 2026
Flood Risk in San Joaquin, CA
San Joaquin, CA has a Flood Risk Score of 22/100 (Grade B), ranking #123 of 3,277 counties nationwide. The risk level is Moderate. There have been 17 NFIP flood-insurance claims totaling $1,095,649 in payouts, with 13 federal disaster declarations on record.
Key Data
What the Grade Means Here
San Joaquin carries a B grade — modest but non-trivial flood risk. With a composite score of 22 and 17 NFIP claims on file, the county sits in the second-safest tier of the U.S. distribution (rank #123 of 3,277). Most insured loss here clusters in localized low-elevation neighborhoods or river-adjacent corridors rather than across the whole county.
Within California, San Joaquin runs 8 points above the state average composite score of 14 — meaningfully more flood-exposed than the typical county in the state. Rank: #1 of 59. The full California state profile shows how every county within the state compares.
What's Driving the Risk Score?
The single biggest driver of the composite score in this county is year-over-year trend (15% of the formula, factor score 100). For San Joaquin, that means the year-over-year trend in flood losses is contributing meaningfully — this is a county where loss has been climbing in recent years, not just historically high.
The trend factor is high (100 of 100), meaning flood losses have been accelerating sharply in this county. That is the single most actionable signal in the score — recent risk is meaningfully greater than the long-run average suggests.
Score Breakdown
| Factor | Score | Weight |
|---|---|---|
| Claims Density | 0 | 40% |
| Disaster Frequency | 28 | 25% |
| Claim Severity | 0 | 20% |
| Year-over-Year Trend | 100 | 15% |
How This Score Is Calculated
The composite is a weighted average of four FEMA-derived factors. Source data comes from the public FEMA flood-mapping program via the OpenFEMA API. For property-level decisions, layer this with the parcel's FEMA Flood Insurance Rate Map zone and recent crest readings from USGS Water Data. Full math: methodology page.
Frequently Asked Questions
What is the flood risk in San Joaquin, CA?
San Joaquin, CA has a Flood Risk Score of 22/100 (Grade B), ranking #123 of 3,277 counties nationwide. The risk level is Moderate. There have been 17 NFIP flood-insurance claims totaling $1,095,649 in payouts, with 13 federal disaster declarations on record.
Is flood insurance required in San Joaquin?
Federal law requires flood insurance for any property in a Special Flood Hazard Area (FEMA Zone A or V) financed by a federally regulated lender. San Joaquin's county-wide composite score is 22 (Grade B), which is a county aggregate — your specific parcel's flood-zone designation comes from the FEMA Flood Insurance Rate Map (FIRM) at fema.gov/flood-maps. Even when not legally required, NFIP coverage is often available for a few hundred dollars a year in moderate- and low-risk zones, and FEMA reports more than 25% of all NFIP claims come from outside high-risk zones.
What is driving the flood risk score in San Joaquin?
The single biggest driver of the composite score in this county is year-over-year trend (15% of the formula, factor score 100). For San Joaquin, that means the year-over-year trend in flood losses is contributing meaningfully — this is a county where loss has been climbing in recent years, not just historically high.
Is flood risk increasing or decreasing in San Joaquin?
The trend factor is high (100 of 100), meaning flood losses have been accelerating sharply in this county. That is the single most actionable signal in the score — recent risk is meaningfully greater than the long-run average suggests.
How does San Joaquin compare to other counties in California?
Within California, San Joaquin runs 8 points above the state average composite score of 14 — meaningfully more flood-exposed than the typical county in the state. Rank: #1 of 59.
Where does this data come from?
Every figure on this page comes from FEMA's public OpenFEMA API — the DisasterDeclarationsSummaries v2 endpoint (federally declared flood-related disasters) and the FimaNfipClaims endpoint (individual NFIP flood-insurance claims aggregated by county FIPS code). Both are public-domain U.S. government work. Real-time stream-gauge readings that complement these federal aggregates live at USGS Water Data. Last updated 2026-05-16.
San Joaquin, CA has a Flood Risk Score of 22/100 (Grade B), ranking #123 of 3,277 counties nationwide. The risk level is Moderate. There have been 17 NFIP flood-insurance claims totaling $1,095,649 in payouts, with 13 federal disaster declarations on record.
The data source behind this answer is FEMA OpenFEMA datasets including the National Flood Hazard Layer and NFIP claims. Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
For readers turning this answer into action: cross-reference against the underlying FEMA OpenFEMA datasets including the National Flood Hazard Layer and NFIP claims record before acting on time-sensitive decisions. The site renders the data as it was published; subsequent revisions can shift the picture, and the live federal data is always the authoritative current reference.