Federal data, rigorously synthesized.
Every CoastalRisk report draws exclusively from authoritative public-sector datasets — FEMA, NOAA, USGS, and OpenFEMA. This page explains exactly what those sources are, how we use them, and where our analysis has limits.
Four federal programs. No proprietary models.
We don't build our own flood models or issue original climate projections. We synthesize what federal agencies have already produced — and make it legible at the parcel level.
National Flood Insurance Program — Flood Map Service Center
FEMA's National Flood Hazard Layer (NFHL) is the authoritative source for flood zone designations in the United States. We pull each property's Special Flood Hazard Area (SFHA) status, flood zone classification (AE, VE, X, etc.), and Base Flood Elevation directly from FEMA's publically accessible NFHL API.
NOAA Tides & Currents — Sea Level Rise Projections
NOAA's Center for Operational Oceanographic Products and Services (CO-OPS) operates the national tide gauge network. We use gauge-specific relative sea level rise rates and the NOAA 2022 Interagency Sea Level Rise Technical Report projections (Intermediate scenario) to produce 2050, 2075, and 2100 outlooks tied to the nearest active gauge.
USGS Coastal Vulnerability Index
The U.S. Geological Survey Coastal Vulnerability Index (CVI) quantifies physical susceptibility to sea level rise along the U.S. shoreline using six variables: geomorphology, shoreline change rate, coastal slope, relative sea level change, mean tidal range, and mean wave height. We use it to contextualize physical exposure independent of flood zone classification.
OpenFEMA — NFIP Claims & Policy Data
OpenFEMA's public NFIP dataset contains decades of claims history by county and community. We use this to quantify historical flood loss — total claim counts and total paid losses — providing an actuarial ground-truth that reflects realized flood damage rather than modeled probability alone.
NOAA SLOSH Model — Storm Surge Maximum of Maximums (MOM)
For Atlantic and Gulf Coast properties, storm surge exposure is drawn from NOAA's Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model. The Maximum of Maximums (MOM) dataset represents the worst-case surge depth for each hurricane category across thousands of modeled storm tracks — it is the same dataset used by NWS forecasters and emergency managers for evacuation planning. For Pacific Coast properties, we reference NOAA tide gauge records and published return-period analyses for El Niño-driven coastal water levels in lieu of hurricane surge data.
From raw data to parcel-level findings.
Pulling data is the easy part. What requires judgment is translating overlapping federal datasets — each with different geographies, update schedules, and methodologies — into findings that are coherent at the scale of a single property.
Address geocoding & coastal proximity check
The property address is geocoded and checked against a coastal boundary layer to confirm it falls within ~20 miles of tidal water. Addresses that fall outside this boundary are not eligible for a CoastalRisk report.
Flood zone classification
The parcel's centroid coordinates are queried against FEMA's National Flood Hazard Layer. We record the flood zone designation, SFHA status, Base Flood Elevation (where available), NFIP community ID, and current CRS discount class. Effective map dates are noted so the client understands how recently the area was studied.
Tide gauge selection & sea level rise projection
We identify the nearest active NOAA CO-OPS tide gauge with an adequate period of record and extract its relative sea level rise trend (mm/yr). This local rate — which captures both global ocean rise and local land subsidence or uplift — is combined with the NOAA 2022 Intermediate scenario to produce three forward projections: 2050, 2075, and 2100.
Storm surge or coastal water level exposure
For Atlantic and Gulf Coast properties, we extract SLOSH MOM surge depths by hurricane category from NOAA's publicly available dataset for the relevant storm surge basin. Surge depths are reported as approximate inundation above ground, not absolute elevation. For Pacific Coast properties, we reference published return-period analyses and historical tide gauge records to characterize coastal water level hazard by event frequency.
Claims history & insurance market context
OpenFEMA NFIP data is queried at the community level to report historical claim counts and total paid losses. We also summarize the current private flood insurance market conditions for the state and community, including any known carrier withdrawals or legislative developments affecting availability and pricing.
Report assembly & quality review
All findings are assembled into a structured nine-section report. Data points are cross-referenced for internal consistency — for example, flood zone classifications are checked against SLR projections to ensure timeline coherence. Notable findings or data gaps are flagged explicitly rather than omitted.
What a CoastalRisk report is not.
Being explicit about scope is not a weakness — it's what separates a useful analytical tool from a misleading one. The following are outside the scope of every report we produce.
Outside scope
- Licensed engineering assessments, structural evaluations, or site surveys of any kind
- Legal advice, regulatory compliance opinions, or permitting guidance
- Insurance recommendations or coverage determinations
- Original flood modeling or proprietary climate projections beyond published federal datasets
- Property valuation or investment recommendations
- Certification of any kind for lender, regulatory, or governmental submission
- Assessments of inland flooding unrelated to coastal storm surge or tidal inundation
FEMA flood maps are the official basis for NFIP flood insurance requirements, but they have known limitations: many were last studied decades ago, do not account for sea level rise, and can underestimate risk in areas with significant erosion or subsidence. CoastalRisk contextualizes FEMA designations against current sea level trends precisely because the maps alone are insufficient — but neither source is a substitute for a site-specific engineering study when one is warranted.
All data used in CoastalRisk reports is publicly available from the federal agencies cited. Clients are encouraged to verify findings independently and consult licensed professionals before making development, financing, or investment decisions.
How current is the data?
FEMA flood zone data is pulled live at the time of report generation via the FEMA NFHL API. NOAA sea level projections reflect the 2022 Interagency Sea Level Rise Technical Report, the current federal standard. NOAA tide gauge trend data is updated continuously by CO-OPS and reflects the most recent available analysis at the time of report generation. OpenFEMA claims data is updated periodically by FEMA and typically lags by several months to one year.
Because federal flood maps are amended through FEMA's Letter of Map Amendment (LOMA) and Letter of Map Revision (LOMR) processes, a property's official flood zone designation can change. CoastalRisk reports reflect data current as of the generation date and do not automatically update if a LOMA or LOMR is issued afterward.
CoastalRisk reports synthesize publicly available data from FEMA, NOAA, USGS, and OpenFEMA for informational purposes only. They do not constitute licensed engineering assessments, legal advice, or insurance guidance. Flood zone classifications, risk projections, and all data should be independently verified before any development, investment, or financing decision. CoastalRisk is not liable for decisions made on the basis of information contained in its reports.