Swiss Weather MCP Server

A Model Context Protocol (MCP) server that provides AI applications with weather information for any place in Switzerland.

• Forecasts for today and the next 8 days from the MeteoSwiss local forecasts, updated every hour
• Measurements from about 160 SwissMetNet weather stations, updated every 10 minutes
• Any place on the Swiss national map, such as towns, districts, lakes and peaks, from swissNAMES3D
• A bundled MCP client for testing

Data sources. This project is not an official MeteoSwiss product.

• Weather forecasts and measurements: MeteoSwiss Open Data. Source: MeteoSwiss
• Place names: swissNAMES3D. Source: Federal Office of Topography swisstopo

Table of Contents

• Project Structure
• Installation
• Usage
• Available Tools
• Good to Know
• Example Usage with LMStudio
• Resources
• License

Project Structure

swiss-weather-mcp/
├── src/swiss_weather_mcp/
│   ├── server.py           # MCP server and its tools
│   ├── places/             # swisstopo place lookup
│   ├── forecast/           # MeteoSwiss local forecasts
│   ├── measurements/       # MeteoSwiss SwissMetNet measurements
│   └── client.py           # MCP client
├── tests/swiss_weather_mcp/  # Tests
└── .github/workflows/      # CI and release pipelines

Installation

# As a command line tool
uv tool install swiss-weather-mcp

# With the optional MCP client, which pulls in the OpenAI SDK
uv tool install 'swiss-weather-mcp[client]'

# As a library dependency
uv add swiss-weather-mcp  # or: pip install swiss-weather-mcp

From source:

git clone https://github.com/cuolm/swiss-weather-mcp.git
cd swiss-weather-mcp
uv sync --extra client  # or, in a virtual environment: pip install -e ".[client]"

No configuration is needed, the server reads everything it requires from MeteoSwiss and swisstopo.

Usage

Running the Server

# stdio (default)
swiss-weather-mcp-server

# streamable-http
swiss-weather-mcp-server --transport=streamable-http --host=localhost --port=8050

From a source checkout, put uv run in front. --help lists all flags.

Note: The cache lives in your OS cache directory, such as ~/Library/Caches/swiss-weather-mcp on macOS or ~/.cache/swiss-weather-mcp on Linux. Set SWISS_WEATHER_MCP_CACHE_DIR to move it. The first start downloads the swissNAMES3D archive (about 33 MB).

MeteoSwiss publishes a new forecast run every hour, each hourly parameter as one file of about 30 to 34 MB for all forecast points. By default the server downloads such a file for every new forecast point and keeps only that point's rows. With --cache-all-forecast-points it keeps the whole files, so further places in the same run need no new download. This helps when many places are asked within the hour, at the cost of disk space.

Running the Server with Docker

Images are built and published automatically by GitHub Actions to the project's GitHub Container Registry, tagged :latest (newest release) and by version.

1. Run the published image, mapping port 8050:

   docker run -p 8050:8050 ghcr.io/cuolm/swiss-weather-mcp:latest
   

2. Access the server at:

   http://localhost:8050/mcp/
   

Note: The cache lives inside the container and is lost when it stops. Mount a volume to keep it across restarts, for example -v swiss-weather-cache:/root/.cache/swiss-weather-mcp.

Manual Build

docker build -t swiss-weather-mcp .
docker run -p 8050:8050 swiss-weather-mcp

Running the MCP Client using Stdio Transport

The bundled MCP client tests the server over stdio. It needs the client extra (see Installation) and starts the MCP server itself, but not the LLM, which has to be running first, for example in llama-server.

1. Install llama.cpp, which provides llama-server, as its installation guide describes. With Homebrew on macOS or Linux:

   brew install llama.cpp
   

2. Start llama-server with a model in its own terminal. It downloads the model on first use:

   llama-server --jinja --no-mmproj -hf unsloth/Qwen3.5-4B-GGUF --port 8080
   

   --jinja uses the model's chat template, which tool calling needs (the default in current llama.cpp), and --no-mmproj skips the vision projector.
3. Run the client against it in a second terminal:

   swiss-weather-mcp-client --model=unsloth/Qwen3.5-4B-GGUF --base-url=http://localhost:8080/v1
   
   # From a source checkout, using uv
   uv run --extra client swiss-weather-mcp-client --model=unsloth/Qwen3.5-4B-GGUF --base-url=http://localhost:8080/v1
   

   --base-url is the server's OpenAI compatible API, and --model the name it lists under /v1/models.

Available Tools

The forecast tools take a location (the name of a place, such as "Zurich") and a Swiss local time, or a date for forecast_daily. Every tool that takes a location also takes an optional near, only needed when several places share the name (see Locations). Each answer holds the forecast, the place and the MeteoSwiss forecast point used, with their altitudes and distance, the time it applies to, and the model run.

Good to Know

Times

• Send times as Swiss clock time in ISO 8601, such as "2026-09-23T14:00"; the server applies summer or winter time.
• Answers give times with their UTC offset, such as 2026-09-23T13:00+02:00.
• An hourly value stamped 14:00 covers 13:00 to 14:00. Cloud cover and the freezing level are values at that moment.
• The forecast covers today and the next 8 days. For "tomorrow" or "tonight", ask current_date_and_time() first.

Locations

• A location is a place name from swissNAMES3D: a town, village, city district, peak, pass, lake, glacier, valley or railway station, such as Zürich, Oerlikon, Titlis or Zürichsee.
• Case and accents are ignored, and English names such as Geneva work too.
• A name of several places, such as Blausee, needs near: a village next to the one the user means, such as near="Riederalp". Without it, the tool lists every place, each with a village to pass as near:

  'Blausee' is the name of 6 places. [...] The biggest first:
    near="Blausee-Mitholz": district and lake, fewer than 20 people, 887 m
    near="Ramiswil": settlement, fewer than 20 people, 683 m
    ...
  

• An unknown name gets suggestions, such as Davos Dorf and Davos Platz for Davos.

Forecast Points

• The forecast comes from a MeteoSwiss forecast point near the place, and every answer names it.
• Weather changes faster with height than with distance: in the standard atmosphere, air cools by 0.65 °C per 100 m.
• So among the points within 5 km, the server takes the one with the smallest distance plus 20 times the height gap: 100 m of height gap counts like 2 km of distance. Without a point within 5 km, it takes the nearest one.
• The factor 20 was tested on the real data: up to 20, the height gaps of lakes and peaks shrink a lot, and every town of 1,000 people or more still gets a point within 3 km.

Measurements

• current_conditions uses one of the about 160 SwissMetNet stations that measure the temperature, chosen like the forecast point: the smallest distance plus 20 times the height gap. Stations are far fewer than forecast points, so the station can still be far from the place and higher or lower.
• Every answer starts with a sentence that says so, such as "The measurements for Braunwald (1290 m) are those of the MeteoSwiss station Elm (958 m), 13.5 km away and 332 m lower."
• current_extremes lists the first 5 stations by temperature or gust, and for the sunniest and the wettest counts the sunny or rainy stations in Switzerland and in each canton.

Forecast Values Are Medians

• Temperature and rain are the median of the many possible outcomes MeteoSwiss calculates, not the most likely value.
• Medians do not add up: when showers are possible but unlikely in any single hour, every hour shows 0 mm while the day still has several millimetres.
• Use forecast_daily for the rain of a day, and forecast_rain for the chance and how much a wet hour may bring.

Example Usage with LMStudio

Using the streamable-http transport layer

Configure the mcp.json file in LMStudio:

{
  "mcpServers": {
    "swiss_weather_mcp_server": {
      "url": "http://localhost:8050/mcp/"
    }
  }
}

Run the MCP server with the streamable-http transport layer:

swiss-weather-mcp-server --transport=streamable-http --host=localhost --port=8050

Using the stdio transport layer

Configure the mcp.json file in LMStudio. Replace <path-to> so the command is the full path that which swiss-weather-mcp-server prints:

{
  "mcpServers": {
    "swiss_weather_mcp_server": {
      "command": "<path-to>/swiss-weather-mcp-server"
    }
  }
}

Resources

• Meteo Swiss Open Data
• Local Forecast Notebook Examples
• Automatic Weather Stations (SwissMetNet)
• swissNAMES3D (swisstopo)
• Model Context Protocol
• MCP Server Quickstart

License

Licensed under the Apache License 2.0.