San Mateo County, California: hazard history
What federal records show has already happened here: disaster declarations, storms, and flood insurance claims. This is a record of the past. It is not a forecast and not a hazard score.
At a glance
What this means
- The event NOAA recorded most often here is Strong Wind, with 275 records.
- The costliest single record is Debris Flow in 2006: $13.0M in property damage, in the dollars of that year.
- The deadliest record is Dense Fog in 2024, with 4 deaths.
- FEMA has declared 24 disasters that named this county, most often for flood.
- The worst year for flood insurance claims was 1998, with 236 claims.
What this can't tell you
- What happens next. Past events do not set the odds of the next one.
- Anything before 1996 from NOAA. That is when NOAA began recording every event type; earlier files hold only tornado, hail and wind, so they are left out on purpose.
- Today's cost. Damage and payments are in the dollars of the year they happened.
- A flood rate. NFIP counts claims but not how many homes were insured, and many flooded homes carry no flood insurance.
- Earthquakes, wildfire perimeters or radar-detected hail. Those records are not tied to counties.
Federal disaster declarations (FEMA)
FEMA declared 24 disasters that named San Mateo County between 1977 and 2023.
| Incident type | Disasters | Most recent |
|---|---|---|
| Flood | 7 | 2023 |
| Severe Storm | 7 | 2023 |
| Fire | 3 | 2020 |
| Biological | 2 | 2020 |
| Coastal Storm | 1 | 1983 |
| Drought | 1 | 1977 |
| Earthquake | 1 | 1989 |
| Freezing | 1 | 1990 |
| Hurricane | 1 | 2005 |
Most recent declarations
- EM-3592 2023 · Flood · Severe Winter Storms, Flooding, Landslides, And Mudslides
- DR-4699 2023 · Severe Storm · Severe Winter Storms, Straight-line Winds, Flooding, Landslides, And Mudslides
- EM-3591 2023 · Flood · Severe Winter Storms, Flooding, And Mudslides
- DR-4683 2022 · Flood · Severe Winter Storms, Flooding, Landslides, And Mudslides
- FM-5336 2020 · Fire · Czu Lightning Fire Complex
- DR-4558 2020 · Fire · Wildfires
- EM-3428 2020 · Biological · Covid-19
- DR-4482 2020 · Biological · Covid-19 Pandemic
- DR-4308 2017 · Flood · Severe Winter Storms, Flooding, And Mudslides
- DR-4305 2017 · Flood · Severe Winter Storms, Flooding, And Mudslides
Not counted above: 34 statewide declarations, which covered every county in California. A declaration is a decision to send federal help, not a measure of how bad an event was. Records run from 1953. Source: FEMA OpenFEMA Disaster Declarations Summaries.
Storms recorded by NOAA, by type
| Event type | Records | Deaths | Injuries | Property damage |
|---|---|---|---|---|
| Strong Wind | 275 | 9 | 9 | $3.5M |
| High Wind | 125 | 1 | 1 | $3.6M |
| Flood | 64 | 0 | 0 | $10.1M |
| Flash Flood | 33 | 1 | 0 | $808K |
| High Surf | 30 | 9 | 18 | $1.7M |
| Debris Flow | 27 | 0 | 0 | $20.1M |
| Thunderstorm Wind | 18 | 0 | 0 | $60K |
| Dense Fog | 17 | 4 | 0 | $25K |
| Heat | 16 | 0 | 0 | $10K |
| Heavy Rain | 12 | 2 | 20 | $2.1M |
| Winter Weather | 10 | 0 | 0 | $0 |
| Coastal Flood | 9 | 0 | 0 | $5K |
| Hail | 9 | 0 | 0 | $30 |
| Rip Current | 8 | 3 | 2 | $0 |
| Wildfire | 8 | 1 | 3 | $0 |
| Excessive Heat | 4 | 3 | 0 | $0 |
| Heavy Snow | 4 | 0 | 0 | $20 |
| Lightning | 4 | 0 | 0 | $0 |
| Dense Smoke | 3 | 0 | 0 | $0 |
| Frost/Freeze | 3 | 0 | 0 | $20K |
| Sneakerwave | 3 | 2 | 2 | $0 |
| Cold/Wind Chill | 2 | 2 | 0 | $0 |
| Tornado | 2 | 0 | 0 | $800K |
| Tsunami | 2 | 0 | 0 | $204K |
Records start in 1996. Damage is NOAA's estimate at the time, in nominal dollars, and is often rounded; it is not insurance claims data. A storm that crossed two NOAA zones in this county is recorded, and counted, once per zone. A storm filed against a forecast zone is counted in every county that zone covers, with the whole storm's damage; do not add these figures across counties.
Year by year
NOAA storm event records in San Mateo County each year. The busiest year was 2019, with 111 records.
Show the numbers for every year
| Year | Records | Deaths | Property damage |
|---|---|---|---|
| 1996 | 2 | 0 | $0 |
| 1997 | 13 | 1 | $0 |
| 1998 | 9 | 1 | $200K |
| 2000 | 2 | 0 | $2.0M |
| 2002 | 1 | 0 | $0 |
| 2004 | 1 | 0 | $50K |
| 2005 | 7 | 0 | $5.8M |
| 2006 | 16 | 1 | $25.4M |
| 2007 | 2 | 2 | $80K |
| 2008 | 16 | 0 | $365K |
| 2009 | 27 | 2 | $3.2M |
| 2010 | 27 | 0 | $3.2M |
| 2011 | 20 | 1 | $808K |
| 2012 | 23 | 1 | $193K |
| 2013 | 18 | 2 | $113K |
| 2014 | 26 | 1 | $636K |
| 2015 | 16 | 0 | $21K |
| 2016 | 4 | 0 | $1.0M |
| 2017 | 72 | 3 | $6K |
| 2018 | 43 | 1 | $30K |
| 2019 | 111 | 5 | $11K |
| 2020 | 51 | 2 | $1K |
| 2021 | 60 | 2 | $500 |
| 2022 | 22 | 3 | $0 |
| 2023 | 32 | 3 | $120 |
| 2024 | 17 | 5 | $40 |
| 2025 | 31 | 1 | $50 |
| 2026 | 19 | 0 | $20 |
Years with no record are left out of the table, not shown as zero.
Notable events
Costliest records
- Debris Flow · Apr 4, 2006$13.0MNOAA name: NWS forecast zone · NOAA record 5497355
- Debris Flow · Apr 1, 2006$7.0MNOAA name: NWS forecast zone · NOAA record 5497353
- Flood · Dec 31, 2005$5.0MNOAA name: San Mateo County · NOAA record 5482519
- Flood · Jan 1, 2006$5.0MNOAA name: San Mateo County · NOAA record 5486536
- High Wind · Oct 13, 2009$2.5MNOAA name: NWS forecast zone · NOAA record 199983
Deadliest records
- Dense Fog · Jan 14, 20244 deathsNOAA name: NWS forecast zone · NOAA record 1147721
- Excessive Heat · Sep 1, 20173 deathsNOAA name: NWS forecast zone · NOAA record 717958
- High Surf · Dec 3, 20072 deathsNOAA name: NWS forecast zone · $80K damage · NOAA record 64859
- Cold/Wind Chill · Dec 2, 20222 deathsNOAA name: NWS forecast zone · NOAA record 1069470
- Flash Flood · Feb 3, 19971 deathNOAA name: San Mateo County · NOAA record 5623562
Each line is one NOAA record, linked to its page at NOAA. One large storm can appear more than once if NOAA recorded it in several zones of this county. Dollars are nominal.
Flood insurance claims (NFIP)
The National Flood Insurance Program paid $20.1M on 1,118 claims in San Mateo County from 1978 to 2024.
| Year | Claims | Paid |
|---|---|---|
| 1998 | 236 | $3.8M |
| 1982 | 147 | $805K |
| 1983 | 106 | $506K |
| 2022 | 97 | $6.0M |
| 1986 | 46 | $241K |
A count of claims, not a rate: NFIP publishes no count of insured homes beside it, and most flood damage is uninsured. Nominal dollars. Records run from 1978 to 2024; claims filed without a county code are not on any county page. Source: FEMA OpenFEMA FIMA NFIP Redacted Claims.
Hazard vulnerability analysis: the probability column for a facility in San Mateo County
A hazard vulnerability analysis rates each hazard for probability, impact, preparedness and response. Probability is the one column the county’s federal record can fill — NCEI storm events from 1996 to 2026 and FEMA declarations naming the county — and this is what it says for a facility here, on the 0–3 scale of the all-hazards structure surveyors expect. The other six columns are the facility’s own judgment about its building, and Calchis leaves them blank.
| Hazard | Prob. | Basis, from the county record |
|---|---|---|
| Severe Thunderstorm | 3 | 31 NCEI events over 31 years (1.00/yr). 7 federal disaster declarations naming the county. |
| Flood, External | 3 | 118 NCEI events over 31 years (3.81/yr). 7 federal disaster declarations naming the county. |
| Wild Fire | 3 | 8 NCEI events over 31 years (0.26/yr). 3 federal disaster declarations naming the county. |
| High Wind (non-convective) | 3 | 400 NCEI events over 31 years (12.90/yr). No federal disaster declaration of this kind has named the county. |
| Hurricane / Tropical Storm | 2 | No events of this kind on the county's NCEI record over 31 years. 2 federal disaster declarations naming the county. |
| Snow Fall / Blizzard / Ice Storm | 2 | 14 NCEI events over 31 years (0.45/yr). No federal disaster declaration of this kind has named the county. |
| Temperature Extremes | 2 | 25 NCEI events over 31 years (0.81/yr). 1 federal disaster declaration naming the county. |
| Drought | 2 | No events of this kind on the county's NCEI record over 31 years. 1 federal disaster declaration naming the county. |
| Earthquake | 2 | 1 federal disaster declaration naming the county. |
| Landslide | 2 | 27 NCEI events over 31 years (0.87/yr). No federal disaster declaration of this kind has named the county. |
| Epidemic | 2 | 2 federal disaster declarations naming the county. |
| Tornado | 1 | 2 NCEI events over 31 years (0.06/yr). No federal disaster declaration of this kind has named the county. |
| Tidal Wave / Tsunami | 1 | 2 NCEI events over 31 years (0.06/yr). No federal disaster declaration of this kind has named the county. |
| Volcano | 1 | No events of this kind on the county's NCEI record over 31 years. No federal disaster declaration of this kind has named the county. |
| Dam Inundation | 1 | No federal disaster declaration of this kind has named the county. |
A dash means the record does not speak to that hazard; it is not a zero. Whether a finished document satisfies the CMS Emergency Preparedness Rule is the facility’s finding and its surveyor’s. Complete the HVA for a facility in San Mateo County — the technological, human and hazardous-materials rows, the six facility columns, the approval and the printed document — or read the sample analysis on that page first.
How this page was made
- Every figure is counted from public federal records held by Calchis: NOAA NCEI Storm Events, FEMA OpenFEMA Disaster Declarations, and FEMA NFIP claims. Nothing is modeled or estimated.
- NOAA files some events against a county and others against an NWS forecast zone, and publishes a code for both. Records are counted as San Mateo County by that code — county records by the county's own FIPS code, zone records through the National Weather Service's published list of which counties each zone covers. No name matching is involved. Of 688 records, 160 were filed against this county and 528 against a forecast zone covering it. A zone storm is counted in every county its zone covers, and its damage figure is the whole storm's, not this county's share — NOAA does not publish that split. So these figures describe this county; they must not be added up across counties. Left out: 29% of California's NOAA records, which are marine zones or zones NWS does not map to a county.
- Counts last rebuilt from the source records on Sep 15, 2026.
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Recorded history from federal public records. Not a hazard score, a risk score, or a forecast, and not a substitute for professional actuarial or emergency-management assessment. Decision-support intelligence — not a primary alerting or dispatch system. Verify against official sources.