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Gridpoints and grids

NWS forecasts use a nationwide 2.5 km × 2.5 km grid system. Each cell represents a small geographic area containing detailed forecast data accessible through the NWS API.

How grid assignment works

Each grid belongs to a Weather Forecast Office (WFO). When you provide a latitude/longitude to the /points endpoint, the API:

  1. Determines which WFO owns that location
  2. Identifies which grid cell contains the point
  3. Returns the grid identifiers needed to request forecasts:
    • gridId-WFO identifier (e.g., BUF, OKX, LWX)
    • gridX / gridY-cell's horizontal and vertical index within that WFO's grid

Use these values to construct forecast requests: /gridpoints/{gridId}/{gridX},{gridY}

Benefits

Grid-cell level forecasts provide:

  • High spatial resolution-Fine-grained local forecasts
  • Consistent structure-Uniform format across all WFOs

Visual example

Forecast grids for the NWS Buffalo Forecast Office

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

Next: Learn how to translate coordinates into Zones →