aemet-mcp

MCP server that exposes public weather data from AEMET (Agencia Estatal de Meteorología, Spain) to AI agents and MCP-compatible clients.

Three tools, well-typed, backed by AEMET's official OpenData API:

• get_municipality_forecast — daily forecast (up to 7 days) for a Spanish municipality, by INE code.
• get_station_observation — last ~12h of hourly observation data (temperature, wind, precipitation…) from a weather station.
• get_weather_warnings — active weather warnings (CAP alerts) for a region or all of Spain.

Prerequisites

• Node.js 20+
• A free AEMET OpenData API key: request one at https://opendata.aemet.es/centrodedescargas/altaUsuario

Installation

No install needed — run it directly with npx:

npx -y @mmillan76/aemet-mcp

The server communicates over stdio, so it's meant to be launched by an MCP client rather than run standalone in a terminal.

Configuration

The server reads the API key from the AEMET_API_KEY environment variable. It exits with an error at startup if it's missing.

Claude Desktop / Claude Code

Add to your MCP client config (e.g. claude_desktop_config.json):

{
  "mcpServers": {
    "aemet": {
      "command": "npx",
      "args": ["-y", "@mmillan76/aemet-mcp"],
      "env": {
        "AEMET_API_KEY": "your-api-key-here"
      }
    }
  }
}

Any other MCP client that supports stdio servers works the same way — point it at npx -y @mmillan76/aemet-mcp with AEMET_API_KEY set in the environment.

Local development

git clone https://github.com/mmillan76/aemet-mcp.git
cd aemet-mcp
npm install
cp .env.example .env   # fill in AEMET_API_KEY
npm run build

Test tool calls interactively with the MCP Inspector:

npx @modelcontextprotocol/inspector node dist/index.js

(the Inspector reads AEMET_API_KEY from your shell environment, so export it — or source .env — before running the command above)

Notes on the AEMET API

AEMET OpenData uses a two-step pattern on every endpoint: the first request returns a JSON envelope with a datos URL, not the actual data; a second request to that URL returns the real payload. This server hides that detail — tools just return the final data. Rate limits apply per API key; if you hit them, the tool returns a clear error instead of retrying silently.

License

MIT — see LICENSE.