FEMA Flood Zone Batch Lookup

Give it a list of US addresses (or latitude/longitude points) and get back, for every one, the official FEMA flood zone, whether it sits in a Special Flood Hazard Area, the base flood elevation, the FIRM panel and its effective date, a plain-English risk label and a link to the FEMA Map Service Center. One row per input, in order, whether or not the address could be located. No API key, no browser, thousands of addresses per run.

Built for flood insurance quoting, mortgage flood-determination pre-screens, real-estate due diligence, portfolio risk reviews and property data enrichment.

What you get per address

Field	Example	Meaning
inputAddress	4802 Braesvalley Dr, Houston, TX 77096	What you sent
id	nola-ae	Your id, or the 1-based position in the list
normalizedAddress	4802 BRAESVALLEY DR, HOUSTON, TX 77096	USPS-style cleaned address
matchedAddress	4802 BRAESVALLEY DR, HOUSTON, TX, 77096	Address the geocoder matched
latitude / longitude	29.6827 / -95.4610	Point used for the lookup
geocoder	census / nominatim / input / none	Which geocoder located it (input = you supplied coordinates)
geocodeConfidence	1	1 exact Census match, 0.7 non-exact Census, 0.5 Nominatim, 0 not found
floodZone	AE	FEMA flood zone code
zoneSubtype	0.2 PCT ANNUAL CHANCE FLOOD HAZARD	Zone qualifier (shaded X, floodway, levee, etc.)
inSFHA	true	Inside a Special Flood Hazard Area (mandatory flood insurance for federally backed mortgages)
staticBFE	-3	Static base flood elevation in feet, when the zone carries one
depth	2	Flood depth in feet for AO zones
verticalDatum	NAVD88	Datum of the BFE
dfirmId	48201C	FEMA study (county) identifier
firmPanel	48201C0865M	Flood Insurance Rate Map panel number
panelEffectiveDate	2019-05-02	Panel effective date
lomrCaseNumber / lomrEffectiveDate	19-04-6434P	Most recent Letter of Map Revision covering the point (only with includeLomr)
riskLabel	High	High, Moderate, Minimal, Undetermined, Open Water or Unmapped
femaMapUrl	https://msc.fema.gov/portal/search?AddressQuery=…	FEMA Map Service Center search for this address
lookupStatus	ok	ok, geocode_failed, not_mapped (no NFHL coverage at this point) or lookup_failed (FEMA service error after retries)
processedAt	ISO timestamp	When the run happened

What the zones mean

Zone	Risk label	Meaning
A, AE, AH, AO, AR, A99	High	1% annual chance (100-year) floodplain. AE has base flood elevations, AH/AO are shallow flooding, AR/A99 relate to levee restoration or construction. Flood insurance is mandatory for federally backed mortgages.
V, VE	High	Coastal 1% annual chance floodplain with wave action. Mandatory insurance, stricter building standards.
X with subtype 0.2 PCT ANNUAL CHANCE FLOOD HAZARD (shaded X, formerly B)	Moderate	0.2% annual chance (500-year) floodplain, or 1% floodplain with less than 1 ft depth. Insurance optional but recommended.
X with subtype AREA WITH REDUCED FLOOD RISK DUE TO LEVEE	Moderate	Protected by an accredited levee; residual risk if the levee fails.
X with subtype AREA OF MINIMAL FLOOD HAZARD (unshaded X, formerly C)	Minimal	Outside the 500-year floodplain.
D	Undetermined	Flood hazards possible but not studied.
OPEN WATER	Open Water	The point falls on a lake, river or the sea.
No polygon	Unmapped	Outside the National Flood Hazard Layer (some rural counties, tribal lands, most of Alaska).

inSFHA comes straight from FEMA's SFHA_TF flag, not from the label, so it is the field to use for mandatory-purchase decisions.

Input

Field	Default	Notes
addresses	5 sample properties	Array of strings ("123 Main St, Austin, TX 78701"), address objects ({"id", "street", "city", "state", "zip"}) or coordinate objects ({"id", "latitude", "longitude"}). Objects may also carry {"id", "address"} for a one-line string with your own id.
includeFirmPanel	true	Add FIRM panel number and effective date
includeLomr	false	Add the latest Letter of Map Revision covering the point
fallbackToNominatim	true	Try OpenStreetMap when the Census Geocoder cannot match an address (1 request/second)
maxItems	10	Process at most this many items

{
  "addresses": [
    "4802 Braesvalley Dr, Houston, TX 77096",
    { "id": "nola-ae", "street": "4900 Paris Ave", "city": "New Orleans", "state": "LA", "zip": "70122" },
    { "id": "denver-point", "latitude": 39.7392, "longitude": -104.9903 }
  ],
  "includeFirmPanel": true,
  "maxItems": 5000
}

Sample output

{
  "inputAddress": "4900 Paris Ave, New Orleans, LA 70122",
  "id": "nola-ae",
  "normalizedAddress": "4900 PARIS AVE, NEW ORLEANS, LA 70122",
  "matchedAddress": "4900 PARIS AVE, NEW ORLEANS, LA, 70122",
  "latitude": 30.0074667765,
  "longitude": -90.074569988723,
  "geocoder": "census",
  "geocodeConfidence": 1,
  "floodZone": "AE",
  "zoneSubtype": null,
  "inSFHA": true,
  "staticBFE": -3,
  "depth": null,
  "verticalDatum": null,
  "dfirmId": "22071C",
  "firmPanel": "22071C0114F",
  "panelEffectiveDate": "2016-09-30",
  "lomrCaseNumber": null,
  "lomrEffectiveDate": null,
  "riskLabel": "High",
  "femaMapUrl": "https://msc.fema.gov/portal/search?AddressQuery=4900%20PARIS%20AVE%2C%20NEW%20ORLEANS%2C%20LA%2C%2070122",
  "lookupStatus": "ok",
  "processedAt": "2026-09-28T18:00:00.000Z"
}

How it works

1. Normalise every address to USPS style (suffix and directional abbreviations, state codes, ZIP+4 split).
2. Geocode with the US Census Bureau batch geocoder (up to 10,000 addresses per request), retry non-matches on the Census one-line endpoint with and without the unit number, then optionally fall back to OpenStreetMap Nominatim. Coordinate inputs skip this step.
3. Query FEMA's National Flood Hazard Layer (NFHL MapServer, layer 28 Flood Hazard Zones) with each point, 5 requests in flight. If the point sits on a boundary between two zones, the SFHA one is reported so a mandatory-purchase zone is never missed.
4. Optionally query the FIRM Panels (layer 3) and LOMRs (layer 1) layers, matched to the same FEMA study as the zone polygon, because neighbouring counties' panel grids overlap.

Throughput is roughly 5–10 lookups per second for geocodable addresses; the Nominatim fallback runs at 1 address per second.

Sources

• FEMA National Flood Hazard Layer, hazards.fema.gov/arcgis/rest/services/public/NFHL/MapServer (the same data behind the FEMA Flood Map Service Center). Zones, BFEs, panels and LOMRs are the currently effective data at run time.
• US Census Bureau Geocoder, Public_AR_Current benchmark.
• OpenStreetMap Nominatim (optional fallback).

Limits and caveats

• This is a point-in-polygon lookup at the geocoded address point. It is not a legal flood zone determination (Standard Flood Hazard Determination Form) and does not replace an elevation certificate. Large parcels can straddle zones; the row reports the zone at the rooftop point the geocoder returned.
• staticBFE is only populated where FEMA stores a static elevation on the zone polygon. Many AE zones carry BFEs on separate BFE lines or cross-sections instead, so a null BFE does not mean there is none.
• Geocoding accuracy follows the Census geocoder (street-segment interpolation). geocodeConfidence below 1 means the point may be a few tens of metres off; treat boundary cases with care.
• Not-yet-effective preliminary maps are not included.
• FEMA's service occasionally returns errors under load; each query is retried four times and the row is marked lookup_failed if it still fails, so you can re-run just those.

Pricing

• $0.005 per run start
• $0.01 per input item (one output row each, charged whether or not the address could be located)

1,000 addresses cost $10.05.