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Weather Forecast Offices (WFOs)

A Weather Forecast Office (WFO) is your regional NWS office that generates forecasts and alerts. When you call /points/{lat,lon}, the API assigns your coordinates to exactly one WFO, which determines all subsequent grid and zone data.

Example: Washington, DC

Requesting /points/38.90,-77.04 returns:

  • gridId: "LWX" → Baltimore/Washington WFO
  • gridX: 96, gridY: 70 → Your forecast grid cell
  • forecastZone: "DCZ001" → Public forecast zone

All forecast data for this location must use WFO LWX.

Where you'll see WFO identifiers

  • /points/{lat,lon} responses (gridId field)
  • /gridpoints/{wfo}/{gridX},{gridY} URLs
  • Forecast and alert metadata

Why this matters

Each WFO manages its own forecast grids. Two nearby coordinates may belong to different WFOs, so always use the WFO returned by /points when requesting gridpoint data.

Map showing WFO coverage areas in the Northeastern United States

Figure: WFO boundaries in the Northeastern US. Notice how coverage areas meet at defined borders—coordinates near these boundaries may resolve to different WFOs.

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 →