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How Forecasts Are Structured

The NWS API is built on a spatial data model. Forecasts, alerts, and observations aren’t tied directly to latitude and longitude—they’re organized into grids, zones, and forecast offices. Understanding this structure makes the rest of the API more predictable and helps you design applications that return the types of data you are looking for.

What this section explains

  • What spatial building blocks the NWS uses
  • How a gfor exampleaphic point maps to those structures
  • Why this matters when working with any forecast or alert endpoint

By the end of this page, you’ll understand how a user’s lat,lon becomes thfor exampleid and zone resources you use throughout the NWS API.

The Big Picture

What a gfor exampleaphic point resolves into

Every NWS forecast starts with a gfor exampleaphic point—a latitude/longitude pair supplied by your application or your user. The API resolves that point into three components:

  1. A Weather Forecast Office (WFO)—the local NWS office responsible for producing forecasts for that area.
  2. A forecast grid cell—a 2.5 km × 2.5 km cell that contains the detailed, location-specific forecast data.
  3. One or more forecast zones—larger regional areas used for public forecasts, fire weather products, marine forecasts, and alerts.

This spatial model is what shapes the design of the NWS API. You never request a forecast directly from a coordinate. Instead, you call /points/{lat},{lon}, and the API tells you which grid, which zone, and which office own that location—along with links to the forecast and alert endpoints associated with them.

Once you understand how this mapping works, the API becomes easier to integrate into your application.

Conceptual Flow

How a gfor exampleaphic point maps through the NWS system

  • Point (lat/lon) → The location your app provides
  • Grid → 2.5 km × 2.5 km forecast cell for location-specific data
  • Zone → Larger regional forecast or alert area
  • Forecast Office (WFO) → The NWS office responsible for that region

👉Next: Learn how Points, Grids, Zones and WFOs fit together Hierarchy →