FEMA Records
24
Above median
California · FEMA + NOAA + National Risk Index
San Mateo County, CA
24 FEMA disaster declarations (1977-2023), with a FEMA National Risk Index rating of Relatively High. Most common hazard: Severe Storm.
- 24
- FEMA declarations
- 17
- Major disasters
- 99
- NRI risk · Relatively High
- Severe Storm
- Top hazard
The verdict
San Mateo County has a nationally busy FEMA history: 24 declarations, more than 66% of counties in this registry. But the state comparison tempers that reading: the total is 16% below the California county mean. FEMA's separate National Risk Index places the county in the riskiest 1%; that score models loss and vulnerability rather than counting declarations.
- Riskiest 1%
- of U.S. counties for FEMA National Risk Index score
- Relatively High
- FEMA National Risk Index rating
- 24
- FEMA declarations vs 21 national county avg
- 1,110
- NFIP flood insurance claims filed
FEMA's National Risk Index and its declaration registry are separate measures. This county's registry includes Fire Management Assistance (FM) records, which are not presidential disaster declarations, alongside Major Disaster (DR) and Emergency (EM) records.
How does San Mateo County compare?
San Mateo County vs. all counties in this dataset
FEMA disaster declarations, all-time
24 Top 34% higher than 66% of 3,266 counties
Each bar is a band; taller bars hold more counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source FEMA Disaster Declarations Summaries v2 · 2026-08-03
San Mateo County's FEMA Risk Index score
FEMA National Risk Index composite score vs. the California county average
What does San Mateo County's hazard record show?
Reading the federal records together
FEMA's NFIP table contains a substantial paid-claim history for this county: 1,110 claims and $20.1M in payments. PlainHazard labels 500 or more claims a heavy registry record; that is a reporting bucket, not an official FEMA risk grade. The average paid claim was $18.1K. NFIP totals exclude uninsured flood losses and do not measure how many properties currently carry a policy.
Start with the state benchmark: a California county averages 28.5 federal declaration records, while San Mateo County has 24. The gap is 16% below that mean. Fewer entries indicate a quieter history of recorded federal actions, not immunity from a hazard and not a prediction about what happens next.
FEMA National Risk Index
This county sits among the highest-risk counties nationally on FEMA's National Risk Index, a composite score of 99.2/100 (Relatively High). Expected Annual Loss is rated Relatively High (roughly $740.0M in annualized losses). Social vulnerability reads Relatively Low and community resilience Very High, both critical modifiers of realized harm here. Of the 18 hazards FEMA models, Earthquake stands out as the sharpest exposure here, rated Relatively High. FEMA's modeled frequency puts that hazard at roughly once every 7 years here.
Declaration frequency
Nationally, San Mateo County's 24 FEMA records form a high-volume history; within California, however, the count is 16% below the county mean. 17 entries carry the Major Disaster classification. The largest incident group is Severe Storm, appearing 7 times. The full 46-year record averages 0.5 declarations annually. A DR label alone does not say whether Individual Assistance, Public Assistance, or both followed.
66 /100
Historical Activity Index
High historical activity
San Mateo County, CA · PlainHazard-derived composite from federal records
This 0–100 index is an explicit PlainHazard composite from FEMA declaration history only on the county surface (this DB has no county-level NOAA damage row) . It is not FEMA's National Risk Index, not a forecast, and not a safety, insurance, or preparedness rating. Open the calculator · Methodology
FEMA Declarations (1953–present) High
17/30
24 OpenFEMA declarations, full ingest window (1.2x national county average)
County Disaster Density Moderate
11/25
24 declarations (0.8x state county average of 29)
Major Disaster Share High
18/25
17 of 24 declarations are major disasters (71%)
Hazard Diversity Very High
20/20
9 different disaster types declared in San Mateo County
Historical Declaration Activity
Activity Band
High
vs. California Avg
-16%
State avg: 28.5
vs. National Avg
+16%
National avg: 20.7
Avg Per Year
0.5
Over 46 years
FEMA NRI 8-hazard radar - San Mateo County
How to read this radar
Each axis: NRI risk rating (Very Low-Very High) on a 0-100 scale. Rounder = broad exposure; spiky = one or two hazards dominate.
Major Disaster share
71%
Major-heavy
NRI risk score
99
Relatively High
Source: FEMA National Risk Index Per-county per-hazard ratings, December 2025 release
How often does each hazard strike San Mateo County?
FEMA's National Risk Index models a historical event count and an annualized frequency for each hazard type. Most hazards are expressed as modeled occurrences per year; FEMA expresses drought and heat-wave frequency as event-days per year. These modeled frequencies are not forecasts.
| Hazard | NRI Risk Rating | Recurrence |
|---|---|---|
| Earthquake | Relatively High | roughly once every 7 years |
| Landslide | Relatively High | an average of 3.9 times per year |
| Riverine Flooding | Relatively High | an average of 1.4 times per year |
| Drought | Relatively High | 38 modeled event-days per year |
| Wildfire | Relatively Moderate | roughly once every 641 years |
| Coastal Flooding | Relatively High | roughly once every 1 years |
| Heat Wave | Relatively Moderate | 4.5 modeled event-days per year |
| Tsunami | Relatively Moderate | roughly once every 3 years |
| Lightning | Relatively Moderate | an average of 4.6 times per year |
| Tornado | Relatively Low | roughly once every 21 years |
| Strong Wind | Relatively Low | roughly once every 37 years |
| Hail | Very Low | roughly once every 42 years |
| Winter Weather | Very Low | roughly once every 2 years |
Source: FEMA National Risk Index Modeled annualized frequency; drought and heat wave use event-days/year, December 2025 release
Disaster Types
Severe Storm 7
Flood 7
Fire 3
Biological 2
Hurricane 1
Freezing 1
Earthquake 1
Coastal Storm 1
Drought 1
What Severe Storm declarations mean here
Severe Storm is the most frequent declaration type on San Mateo County's record, 29% of its declarations. In FEMA's vocabulary this covers convective weather: thunderstorm straight-line winds, large hail, and the multi-day outbreaks that often carry embedded tornadoes. Activity is heaviest in spring and summer, though the season varies by region.
These events behave differently from a hurricane on paper. Damage tends to be distributed along a storm track rather than concentrated on a coastline, and a declaration typically follows an outbreak that crossed several counties over a few days, not a single point of impact. Because the qualifying threshold is the cost of uninsured public and individual losses rather than storm intensity, two similar storms can produce a declaration in one year and none in another.
Declaration counts describe past federal action. They are a record of what was declared, not a forecast of future hazard probability.
Declaration Types
What DR / EM / FM mean
FEMA categorizes declarations as Major Disasters (DR), Emergencies (EM), or Fire Management Assistance (FM).
Major Disaster - 17 70.8%
of all 24 declarations
Emergency - 5 20.8%
of all 24 declarations
Fire Management - 2 8.3%
of all 24 declarations
FEMA Declarations Timeline
| Year | Declarations | |
|---|---|---|
| 2023 | 4 | |
| 2020 | 4 | |
| 2017 | 2 | |
| 2010 | 1 | |
| 2006 | 2 | |
| 2005 | 1 | |
| 1998 | 1 | |
| 1997 | 1 | |
| 1995 | 2 | |
| 1991 | 1 | |
| 1990 | 1 | |
| 1986 | 1 | |
| 1983 | 1 | |
| 1982 | 1 | |
| 1977 | 1 | |
Disaster Declarations
How the 24 FEMA declarations break into federal action codes (DR / EM / FM). Same DISTINCT grain as the table below.
Download these 24 declarations as CSV . FEMA source data is public domain; our derived presentation is CC0.
| DR# | Title | Type | Incident | Date |
|---|---|---|---|---|
| 4699 | SEVERE WINTER STORMS, STRAIGHT-LINE WINDS, FLOODING, LANDSLIDES, AND MUDSLIDES | DR | Severe Storm | 2023-04-03 |
| 3592 | SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES | EM | Flood | 2023-03-10 |
| 4683 | SEVERE WINTER STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES | DR | Flood | 2023-01-14 |
| 3591 | SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES | EM | Flood | 2023-01-09 |
| 4558 | WILDFIRES | DR | Fire | 2020-08-22 |
| 5336 | CZU LIGHTNING FIRE COMPLEX | FM | Fire | 2020-08-20 |
| 4482 | COVID-19 PANDEMIC | DR | Biological | 2020-03-22 |
| 3428 | COVID-19 | EM | Biological | 2020-03-13 |
| 4308 | SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES | DR | Flood | 2017-04-01 |
| 4305 | SEVERE WINTER STORMS, FLOODING, AND MUDSLIDES | DR | Flood | 2017-03-16 |
| 2856 | GLENVIEW FIRE | FM | Fire | 2010-09-10 |
| 1646 | SEVERE STORMS, FLOODING, LANDSLIDES, AND MUDSLIDES | DR | Severe Storm | 2006-06-05 |
| 1628 | SEVERE STORMS, FLOODING, MUDSLIDES, AND LANDSLIDES | DR | Severe Storm | 2006-02-03 |
| 3248 | HURRICANE KATRINA EVACUATION | EM | Hurricane | 2005-09-13 |
| 1203 | SEVERE WINTER STORMS AND FLOODING | DR | Severe Storm | 1998-02-09 |
| 1155 | SEVERE STORMS, FLOODING, MUD AND LANDSLIDES | DR | Severe Storm | 1997-01-04 |
| 1046 | SEVERE WINTER STORMS, FLOODING LANDSLIDES, MUD FLOW | DR | Severe Storm | 1995-03-12 |
| 1044 | SEVERE WINTER STORMS, FLOODING, LANDSLIDES, MUD FLOWS | DR | Severe Storm | 1995-01-10 |
| 894 | SEVERE FREEZE | DR | Freezing | 1991-02-11 |
| 845 | LOMA PRIETA EARTHQUAKE | DR | Earthquake | 1989-10-18 |
Show 4 earlier declaration records
| DR# | Title | Type | Incident | Date |
|---|---|---|---|---|
| 758 | SEVERE STORMS & FLOODING | DR | Flood | 1986-02-21 |
| 677 | COASTAL STORMS, FLOODS, SLIDES & TORNADOES | DR | Coastal Storm | 1983-02-09 |
| 651 | SEVERE STORMS, FLOOD, MUDSLIDES & HIGH TIDE | DR | Flood | 1982-01-07 |
| 3023 | DROUGHT | EM | Drought | 1977-01-20 |
Storm Events in California
Statewide NOAA context only. PlainHazard does not currently attribute these state totals to San Mateo County.
| Storm Type | Events | Fatalities | Injuries | Property Damage |
|---|---|---|---|---|
| High Wind | 4,070 | 13 | 27 | $228.2M |
| Flood | 3,132 | 26 | 25 | $985.1M |
| Heavy Snow | 1,814 | 6 | 0 | $1.6M |
| Dense Fog | 1,605 | 52 | 148 | $2.8M |
| Drought | 1,421 | 0 | 0 | $0 |
Source: NOAA Storm Events Database State-level aggregated data, 2015-2025
NFIP Flood Insurance Claims
Total Claims
1,110
Total Paid
$20.1M
Avg Per Claim
$18.1K
Source: FEMA National Flood Insurance Program (NFIP) OpenFEMA Claims Data
FEMA National Risk Index
Overall Risk
Relatively High
Score: 99.2/100
Expected Annual Loss
Relatively High
$740.0M/year
Social Vulnerability
Relatively Low
Community Resilience
Very High
Hazard Risk Breakdown
Earthquake Relatively High
Landslide Relatively High
Riverine Flooding Relatively High
Drought Relatively High
Wildfire Relatively Moderate
Coastal Flooding Relatively High
Heat Wave Relatively Moderate
Tsunami Relatively Moderate
Lightning Relatively Moderate
Tornado Relatively Low
Strong Wind Relatively Low
Hail Very Low
Winter Weather Very Low
Cold Wave No Rating
Source: FEMA National Risk Index (NRI) Ratings reflect relative scores among all US counties. Data: hazards.fema.gov/nri
The model's sharpest exposure here: Earthquake
Earthquake is the model's clearest example of a hazard with no season and no warning. Its expected loss is driven less by how often shaking occurs than by how much of the building stock predates modern seismic codes, so exposure can be high in places where nothing has happened for a long time.
Worth noting for San Mateo County: the model and the federal record do NOT point at the same hazard. Earthquake carries the highest modeled rating (Relatively High), while the county's declaration history is led by Severe Storm. That is not a contradiction, the two measure genuinely different things. Declarations record federal ACTION, which requires damage costly enough to exceed state and local capacity; the Risk Index models EXPECTED annual loss across all 18 hazards whether or not any declaration ever followed. A hazard can be the county's largest modeled exposure and never once have driven a declaration.
National Risk Index ratings are modeled estimates of expected annual loss, not predictions of what will happen in any given year.
Data-matched county comparisons
San Mateo County's closest FEMA peer: Lauderdale County, MS
Comparisons use published FEMA declaration fields plus the National Risk Index composite for San Mateo County. Record similarity, not a safety rating.
Closest declaration profiles
San Mateo County shows 24 FEMA declarations, led by Severe Storm.
Similar Major-disaster share
San Mateo County: 17 of 24 of its declarations are Major.
Similar modeled NRI score
San Mateo County: NRI composite 99.2 (Relatively High).
How these peers are chosen
Cohort: Published U.S. county equivalents outside the source state or territory. Each metric keeps six ETL candidates; three unique destinations are shown after de-duplicating across axes. Declaration-volume ranking combines count and Major-disaster share and prefers a different leading incident type; Major-share ranks the Major fraction adjusted for volume; NRI ranks the modeled composite score only.
Retained FEMA snapshot feed for San Mateo County - capture-dated entries only.
Further reading for this county
Understanding disaster data
San Mateo County's NFIP claims file (1,110 claims) and FEMA declaration history measure different federal records - this guide separates them from modeled NRI risk.
More PlainHazard guides
- Most disaster-prone counties - U.S. counties ranked by FEMA declaration totals.
- Understanding disaster data - declarations vs storm events vs NRI scores.
- Preparing for natural disasters - household checklist (not county-specific advice).
Related
Frequently Asked Questions
What is the most common disaster type in San Mateo County?
The most common disaster type in San Mateo County is Severe Storm, with 7 declarations. Other disaster types include Flood (7), Fire (3), Biological (2).
How does San Mateo County's FEMA declaration record compare with the California average?
The typical California county has 28.5 FEMA declaration records; San Mateo County has 24, or 16% fewer. Against the national county mean of 20.7, this county's total is 16% higher. The comparison is historical and says nothing about the probability of a future event.
How many major FEMA disaster declarations has San Mateo County received?
San Mateo County has received 17 major disaster declarations, representing 71% of all 24 disaster declarations.
How many flood insurance claims has San Mateo County filed?
San Mateo County has 1,110 National Flood Insurance Program (NFIP) claims totaling $20.1M in payments, with an average of $18.1K per claim.
What was the worst year for disasters in San Mateo County?
The most active year for disaster declarations in San Mateo County was 2020, with 4 declarations. The county has FEMA disaster data spanning 1977 to 2023.
What is the FEMA National Risk Index score for San Mateo County?
According to the FEMA National Risk Index, San Mateo County, California has an overall risk score of 99.2 out of 100 (Relatively High). On social vulnerability the county rates Relatively Low; on community resilience, Very High. The Expected Annual Loss (EAL) score is Relatively High, representing $740.0M in annualized losses.
Which natural hazard poses the greatest risk to San Mateo County?
FEMA's NRI data points to San Mateo County is Earthquake (risk rating: Relatively High). Other significant hazards include Landslide (Relatively High) and Riverine Flooding (Relatively High). FEMA's modeled event frequency puts earthquake here at roughly once every 7 years. FEMA derives these ratings from historical event frequency, the assets exposed, and the community's vulnerability profile.
Data Sources & Methodology
Disaster declaration data comes from the FEMA OpenFEMA Disaster Declarations Summaries v2 API, which includes all federally declared disasters, emergencies, and fire management assistance grants.
Storm event data is sourced from the NOAA Storm Events Database (2015-2025), which tracks significant weather events including thunderstorms, tornadoes, floods, and winter storms.
Flood insurance data comes from the FEMA National Flood Insurance Program (NFIP) OpenFEMA claims dataset.
This data is provided for informational purposes only. FEMA disaster declarations represent federal response actions and may not capture all local emergencies or weather events.
What this means for San Mateo County
Against a California county mean of 29 declarations, San Mateo County, CA records 24, or 16% fewer. PlainHazard classifies that historical total as high activity.
- Major Disaster is the largest group (17 of 24) in a declaration history that remains below its state benchmark; frequency here is not a forecast. California overview
- Nationally the county exceeds 66% of recorded county totals, but its own California benchmark is higher. The ranking keeps those two contexts separate. Most-disaster rankings
- The large NFIP claims file and FEMA declaration history measure different federal records; the guide explains where they overlap and where they do not. Disaster-data guide
A below-average federal record is not a safety guarantee. Use National Weather Service alerts and local emergency-management notices for present conditions, not this historical comparison.
PlainHazard derives this profile from FEMA's Disaster Declarations Summaries and National Risk Index data. The declaration comparison covers 3,266 U.S. counties and county equivalents in this database, refreshed as of 2026-08-03. Read our methodology - how this data is sourced, computed, and verified.
All federal data sources used on this page
- FEMA OpenFEMA, Disaster Declarations Summaries v2 - all federally-declared disasters for this county. fema.gov/openfema/disaster-declarations
- FEMA National Risk Index (NRI) - per-county per-hazard risk ratings and expected annual loss. hazards.fema.gov/nri
- NOAA NCEI Storm Events Database - state-level storm/severe-weather event records, 2015-2025. ncdc.noaa.gov/stormevents
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainHazard Editorial
Verify with FEMA → · Verify with FEMA NRI → · Verify with NOAA →
Every figure on PlainHazard is rendered directly from FEMA federal disaster data, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or national statistics report, the data & editorial changelog, or report a data error.