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Weather Forecast Offices (WFOs)

What is a WFO?

A Weather Forecast Office (WFO) is the local NWS office responsible for generating the forecast and alert data for a specific region. When you call /points/{lat,lon}, the API resolves your point to exactly one WFO before determining grid and zone information.

Example:
A user at 38.90, –77.04 (Washington, DC) requests /points/38.90,-77.04.

The API returns:

  • "gridId": "LWX" → Weather Forecast Office: Baltimore/Washington
  • "gridX": 96, "gridY": 70 → Forecast grid cell
  • "forecastZone": "DCZ001" → Public forecast zone
  • "county": "District of Columbia" → County/zone metadata

This tells your application that all forecast and gridpoint data should be requested from WFO LWX.

What a WFO represents

  • A regional operational office responsible for forecasts and local weather products
  • Defines the spatial domain wherfor exampleidpoint and zone data originate
  • Appears in API URLs as a short identifier (for example, LWX, OKX, SEW)

Northeast US WFOs

Figure: Weather Forecast Offices for the Northeastern US.

Where WFOs appear in the API

Common places you'll encounter WFO identifiers

  • In /points/{lat,lon} responses under gridId
  • In /gridpoints/{office}/{gridX},{gridY} URLs
  • In metadata fields for forecast or alert products

Why WFOs matter

Each WFO manages its own forecast grids and zones. This means:

  • Thfor exampleid and zone definitions for a point depend on the WFO it falls into
  • Two nearby coordinates may belong to different WFOs
  • All /gridpoints/... forecast data must be fetched using the correct WFO code

Quick visualization

flowchart LR
  P["/points/{lat,lon}"] --> W["WFO (gridId)"]
  W --> G["gridpoints/{WFO}/{gridX},{gridY}"]
  W --> Z["Zones owned by the WFO"]

Example WFO identifiers

  • LWX—Baltimore/Washington
  • OKX—New York City
  • SEW—Seattle
  • MFL—Miami
  • BOU—Boulder

Developer takeaway

Always use the WFO returned by /points/{lat,lon} when requesting forecasts, gridpoint data, or zone-based alerts.

👉Next: Learn about Gridpoints and Grids →