get-forecast
Retrieve weather forecast data for specific geographic coordinates using latitude and longitude parameters.
Instructions
Get weather forecast for a location
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| latitude | Yes | Latitude of the location | |
| longitude | Yes | Longitude of the location |
Implementation Reference
- src/index.ts:123-215 (handler)Full handler implementation for the 'get-forecast' tool, registered directly in the MCP server. It takes latitude and longitude, queries the NWS API for points and forecast data using the makeNWSRequest helper, formats the periods, and returns a text content block with the forecast.
server.tool( "get-forecast", "Get weather forecast for a location", { latitude: z.number().min(-90).max(90).describe("Latitude of the location"), longitude: z .number() .min(-180) .max(180) .describe("Longitude of the location"), }, async ({ latitude, longitude }) => { // Get grid point data const pointsUrl = `${NWS_API_BASE}/points/${latitude.toFixed( 4 )},${longitude.toFixed(4)}`; const pointsData = await makeNWSRequest<PointsResponse>(pointsUrl); if (!pointsData) { return { content: [ { type: "text", text: `Failed to retrieve grid point data for coordinates: ${latitude}, ${longitude}. This location may not be supported by the NWS API (only US locations are supported).`, }, ], }; } const forecastUrl = pointsData.properties?.forecast; if (!forecastUrl) { return { content: [ { type: "text", text: "Failed to get forecast URL from grid point data", }, ], }; } // Get forecast data const forecastData = await makeNWSRequest<ForecastResponse>(forecastUrl); if (!forecastData) { return { content: [ { type: "text", text: "Failed to retrieve forecast data", }, ], }; } const periods = forecastData.properties?.periods || []; if (periods.length === 0) { return { content: [ { type: "text", text: "No forecast periods available", }, ], }; } // Format forecast periods const formattedForecast = periods.map((period: ForecastPeriod) => [ `${period.name || "Unknown"}:`, `Temperature: ${period.temperature || "Unknown"}°${ period.temperatureUnit || "F" }`, `Wind: ${period.windSpeed || "Unknown"} ${period.windDirection || ""}`, `${period.shortForecast || "No forecast available"}`, "---", ].join("\n") ); const forecastText = `Forecast for ${latitude}, ${longitude}:\n\n${formattedForecast.join( "\n" )}`; return { content: [ { type: "text", text: forecastText, }, ], }; } ); - src/index.ts:126-133 (schema)Zod input schema for the get-forecast tool, validating latitude (-90 to 90) and longitude (-180 to 180).
{ latitude: z.number().min(-90).max(90).describe("Latitude of the location"), longitude: z .number() .min(-180) .max(180) .describe("Longitude of the location"), }, - src/index.ts:123-215 (registration)MCP server tool registration for 'get-forecast', including name, description, schema, and inline handler.
server.tool( "get-forecast", "Get weather forecast for a location", { latitude: z.number().min(-90).max(90).describe("Latitude of the location"), longitude: z .number() .min(-180) .max(180) .describe("Longitude of the location"), }, async ({ latitude, longitude }) => { // Get grid point data const pointsUrl = `${NWS_API_BASE}/points/${latitude.toFixed( 4 )},${longitude.toFixed(4)}`; const pointsData = await makeNWSRequest<PointsResponse>(pointsUrl); if (!pointsData) { return { content: [ { type: "text", text: `Failed to retrieve grid point data for coordinates: ${latitude}, ${longitude}. This location may not be supported by the NWS API (only US locations are supported).`, }, ], }; } const forecastUrl = pointsData.properties?.forecast; if (!forecastUrl) { return { content: [ { type: "text", text: "Failed to get forecast URL from grid point data", }, ], }; } // Get forecast data const forecastData = await makeNWSRequest<ForecastResponse>(forecastUrl); if (!forecastData) { return { content: [ { type: "text", text: "Failed to retrieve forecast data", }, ], }; } const periods = forecastData.properties?.periods || []; if (periods.length === 0) { return { content: [ { type: "text", text: "No forecast periods available", }, ], }; } // Format forecast periods const formattedForecast = periods.map((period: ForecastPeriod) => [ `${period.name || "Unknown"}:`, `Temperature: ${period.temperature || "Unknown"}°${ period.temperatureUnit || "F" }`, `Wind: ${period.windSpeed || "Unknown"} ${period.windDirection || ""}`, `${period.shortForecast || "No forecast available"}`, "---", ].join("\n") ); const forecastText = `Forecast for ${latitude}, ${longitude}:\n\n${formattedForecast.join( "\n" )}`; return { content: [ { type: "text", text: forecastText, }, ], }; } ); - src/tools/weather.ts:4-20 (helper)Utility function makeNWSRequest used by get-forecast (and get-alerts) to perform authenticated fetch requests to NWS API endpoints.
export async function makeNWSRequest<T>(url: string): Promise<T | null> { const headers = { "User-Agent": USER_AGENT, Accept: "application/geo+json", }; try { const response = await fetch(url, { headers }); if (!response.ok) { throw new Error(`HTTP error! status: ${response.status}`); } return (await response.json()) as T; } catch (error) { console.error("Error making NWS request:", error); return null; } }