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Gridpoints and Grids

NWS forecasts are built on a nationwide set of 2.5 km × 2.5 km grid cells. Each cell represents a small geographic area and contains the detailed, point-level forecast data your application retrieves through the NWS API.

Each grid belongs to a Weather Forecast Office (WFO). When a user provides a latitude/longitude, the /points endpoint determines which WFO owns that location and which grid cell the point falls into. The API then returns the grid identifiers you’ll use to request the actual forecast:

  • gridId—the WFO identifier (for example, BUF, OKX, LWX)
  • gridX / gridY—the cell’s horizontal and vertical index within that WFO’s grid

Together, these values define the path to the forecast resources under /gridpoints/{gridId}/{gridX},{gridY}.

Because forecasts are generated at thfor exampleid-cell level, this structurfor exampleves you:

  • High spatial resolution (finfor exampleained local forecasts)
  • Consistent structure across all WFOs

Below is an illustration of how the grid subdivides the area covered by a WFO:

Forecast grids for the NWS Buffalo Forecast Office

Figure: Buffalo NWS office (BUF) with 2.5 km forecast grid cells (gridX, gridY)

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