San Mateo County flood history
California · From FEMA's flood insurance and disaster data · Updated 2026-10-08
FEMA's National Flood Insurance Program (NFIP) data lists 1,110 flood insurance claims in San Mateo County, California since 1978. The NFIP paid $20.1 million on them (building, contents and Increased Cost of Compliance payments, in the dollars of the year paid).
The year with the most claims was 1998, with 236, mostly from Pineapple Express - Southern.
In the last ten years (2017–2026) there were 220 claims, and the average paid claim was $64,320.
47% of the claims with a recorded flood zone came from buildings outside FEMA's high-risk zones (rated zones B, C and X).
About 1.8% of homes in San Mateo County, California had an NFIP flood policy in FEMA's latest count (3,346 of 182,415 residential buildings). In the high-risk flood zones (Special Flood Hazard Areas), it was 31% (2,178 of 7,052).
Since 2000, FEMA has made 8 flood-related disaster declarations covering San Mateo County, California. The most recent was DR-4699-CA (Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides), declared April 3, 2023.
NFIP claims by year
Show as a table
| Year | Claims | Paid |
|---|---|---|
| 2026 | 1 | $0 |
| 2025 | 4 | $164,289 |
| 2024 | 2 | $0 |
| 2023 | 27 | $659,707 |
| 2022 | 97 | $6.0 million |
| 2021 | 44 | $2.6 million |
| 2020 | 7 | $137,352 |
| 2019 | 4 | $7,766 |
| 2018 | 6 | $118,238 |
| 2017 | 28 | $483,875 |
| 2016 | 20 | $195,215 |
| 2015 | 5 | $60,654 |
| 2014 | 35 | $1.1 million |
| 2013 | 3 | $3,238 |
| 2012 | 15 | $95,269 |
| 2011 | 7 | $36,063 |
| 2010 | 18 | $88,825 |
| 2009 | 6 | $95,665 |
| 2008 | 14 | $95,218 |
| 2006 | 12 | $218,854 |
| 2005 | 17 | $1.3 million |
| 2004 | 13 | $123,757 |
| 2003 | 2 | $18,817 |
| 2002 | 26 | $806,452 |
| 2001 | 14 | $43,738 |
| 2000 | 6 | $23,474 |
| 1999 | 6 | $2,654 |
| 1998 | 236 | $3.8 million |
| 1997 | 9 | $2,418 |
| 1996 | 11 | $44,231 |
| 1995 | 24 | $58,796 |
| 1994 | 4 | $43,513 |
| 1993 | 10 | $27,938 |
| 1992 | 5 | $14,872 |
| 1991 | 1 | $0 |
| 1989 | 8 | $120,190 |
| 1988 | 1 | $7,643 |
| 1987 | 10 | $26,460 |
| 1986 | 42 | $171,208 |
| 1985 | 2 | $0 |
| 1984 | 2 | $0 |
| 1983 | 85 | $356,270 |
| 1982 | 156 | $906,144 |
| 1981 | 6 | $5,796 |
| 1980 | 25 | $127,125 |
| 1979 | 16 | $7,080 |
| 1978 | 18 | $21,739 |
Named flood events
| Event | Year | Claims | Paid |
|---|---|---|---|
| California Atmospheric River | 2022 | 93 | $6.0 million |
| Pineapple Express - Southern | 1998 | 219 | $3.7 million |
| Flooding | 1982 | 116 | $832,729 |
| California Atmospheric River | 2023 | 26 | $624,545 |
| Flooding | 1983 | 50 | $197,837 |
| Flooding | 1986 | 39 | $167,386 |
| Flooding | 1980 | 19 | $122,752 |
| Winter storm | 2010 | 9 | $74,082 |
How many homes have flood insurance
FEMA counts 3,346 residential NFIP policies in San Mateo County, against 182,415 residential buildings (1.8%). Of the 7,052 residential buildings in high-risk flood zones (Special Flood Hazard Areas), 2,178 have an NFIP policy (31%). Private flood policies aren't in these counts.
Whether you're required to carry flood insurance depends on your flood zone and your mortgage. See do I need flood insurance?
What flood insurance costs in San Mateo County
On June 30, 2026, 4,170 NFIP flood insurance policies were in force in San Mateo County, California. For the 3,011 single-family homes among them, the typical (median) yearly cost was about $1,240; the average was $1,420.
| Rated flood zone | Policies | Typical yearly cost, single-family home | Average cost | Average building coverage |
|---|---|---|---|---|
| High-risk zones (A and V) | 2,824 | $1,290 | $1,550 | $244,000 |
| Moderate- and low-risk zones (B, C and X) | 1,345 | $1,110 | $1,180 | $241,000 |
Cost here is what FEMA's data lists as the policy cost: the premium plus the reserve fund assessment, federal policy fee and HFIAA surcharge. It covers single-family homes only (not condos, apartments or businesses), with costs rounded to the nearest $10 and shown only where at least 20 homes back the figure. Your own price depends on your building and the coverage you choose; see how flood insurance is priced. Private flood insurance isn't included.
Flood-related disaster declarations
| Declaration | Declared | Event | Help for individuals |
|---|---|---|---|
| DR-4699-CA | Apr 3, 2023 | Severe Winter Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides | Yes |
| EM-3592-CA | Mar 10, 2023 | Severe Winter Storms, Flooding, Landslides, and Mudslides | No |
| DR-4683-CA | Jan 14, 2023 | Severe Winter Storms, Flooding, Landslides, and Mudslides | Yes |
| EM-3591-CA | Jan 9, 2023 | Severe Winter Storms, Flooding, and Mudslides | No |
| DR-4308-CA | Apr 1, 2017 | Severe Winter Storms, Flooding, and Mudslides | No |
| DR-4305-CA | Mar 16, 2017 | Severe Winter Storms, Flooding, and Mudslides | No |
| DR-1646-CA | Jun 5, 2006 | Severe Storms, Flooding, Landslides, and Mudslides | No |
| DR-1628-CA | Feb 3, 2006 | Severe Storms, Flooding, Mudslides, and Landslides | Yes |
Check your own address
County numbers can't tell you about a single building. Look up your property on FEMA's flood map, then read what your flood zone means. More counties: all of California.
Where these numbers come from
All figures on this page are calculated from FEMA's public OpenFEMA datasets:
- NFIP Redacted Claims (v3) (FEMA (OpenFEMA)): NFIP claims since 1978, downloaded 2026-10-08. Dollar amounts are what the NFIP paid, not adjusted for inflation. Claims filed under private flood insurance aren't included.
- NFIP Residential Penetration Rates (v1) (FEMA (OpenFEMA)): NFIP residential policy contracts in force (as of August 3, 2026) divided by FEMA's count of residential buildings from the National Structure Inventory. FEMA notes that inventory is incomplete in some counties, which can inflate the rate. Private flood policies aren't counted.
- NFIP Redacted Policies (v3) (FEMA (OpenFEMA)): NFIP policies in force on June 30, 2026 (a policy counts if its term covers that date and it wasn't cancelled), downloaded 2026-10-08. Policy counts are FEMA's insured units, so a condominium association policy counts each unit. Costs are FEMA's "policy cost" (premium plus reserve fund assessment, federal policy fee and HFIAA surcharge) for single-family homes only. Policies FEMA's data doesn't place in a county count toward the state only.
- Disaster Declarations Summaries (v2) (FEMA (OpenFEMA)): disaster declarations, downloaded 2026-10-08. We count a declaration as flood-related when FEMA lists flooding (or a dam or levee break) as its incident type or a designated incident type, or the declaration's title mentions flooding.
FEMA's redacted claims data doesn't identify properties, and FEMA notes that some records lack a county or flood zone. See how we use the data.