Open Meteo MCP Server

A Model Context Protocol (MCP) server providing weather and snow condition tools via the Open-Meteo API.

Version 3.3.0 - Full type safety, automated quality checks, 90% test coverage!

Features

Core Capabilities

• Geocoding: Search locations by name instead of coordinates

• Weather Forecasts: Get current weather and multi-day forecasts for any location

• Snow Conditions: Get snow depth, snowfall, and mountain weather data

• Air Quality: Monitor AQI, pollutants, UV index, and pollen levels

• MCP Resources: Weather codes, ski resort coordinates, AQI reference, Swiss locations

• MCP Prompts: Guided workflows for ski trips, outdoor activities, and travel planning

• Free API: No API key required - powered by Open-Meteo's free weather API

• MCP Integration: Seamlessly integrates with MCP-compatible clients like Claude Desktop

Quality & Reliability (Phase 8 Complete)

• Type Safety: 0 mypy errors, full type annotations across codebase

• Code Quality: 100% ruff formatting and linting compliant

• Error Handling: Standardized error handling decorators across all tools (Phase 8)

• Automated Checks: Pre-commit hooks enforce quality on every commit

• Test Coverage: 248+ tests passing, 90%+ code coverage

• Production Ready: Fully tested, documented, and ready for deployment

Related MCP server: Open-Meteo MCP Server

Tools

search_location

Search for locations by name to get coordinates (NEW in v2.1).

Parameters:

• name (required): Location name to search

• count (optional): Number of results (1-100, default: 10)

• language (optional): Language for results (default: "en")

• country (optional): Country code filter (e.g., "CH" for Switzerland)

Example: search_location(name="Zurich") → Returns coordinates, elevation, timezone

get_weather

Get weather forecast for a location with temperature, precipitation, humidity, and more.

Parameters:

• latitude (required): Latitude in decimal degrees

• longitude (required): Longitude in decimal degrees

• forecast_days (optional): Number of forecast days (1-16, default: 7)

• include_hourly (optional): Include hourly forecasts (default: true)

• timezone (optional): Timezone for timestamps (default: "auto")

Enhanced in v2.1: Now includes precipitation probability, apparent temperature, UV index, cloud cover, visibility, wind gusts

get_snow_conditions

Get snow conditions and forecasts for mountain locations.

Parameters:

• latitude (required): Latitude in decimal degrees

• longitude (required): Longitude in decimal degrees

• forecast_days (optional): Number of forecast days (1-16, default: 7)

• include_hourly (optional): Include hourly data (default: true)

• timezone (optional): Timezone for timestamps (default: "Europe/Zurich")

Enhanced in v2.1: Now includes wind chill, cloud cover, precipitation probability

get_air_quality

Get air quality forecast including AQI, pollutants, UV index, and pollen (NEW in v2.1).

Parameters:

• latitude (required): Latitude in decimal degrees

• longitude (required): Longitude in decimal degrees

• forecast_days (optional): Number of forecast days (1-5, default: 5)

• include_pollen (optional): Include pollen data (default: true, Europe only)

Returns: European/US AQI, PM10, PM2.5, O3, NO2, SO2, CO, UV index, pollen counts

Resources

The server provides MCP resources for reference data:

weather-codes

WMO weather code reference with descriptions, categories, and travel impact.

• URI: weather://codes

• Format: JSON

• Content: 28 weather codes with interpretations

...existing code...

swiss-locations

Popular Swiss locations with coordinates (NEW in v2.1).

• URI: weather://swiss-locations

• Format: JSON

• Content: Cities, mountains, passes, and lakes

aqi-reference

Air Quality Index interpretation guide (NEW in v2.1).

• URI: weather://aqi-reference

• Format: JSON

• Content: European/US AQI scales, UV index, pollen levels, health recommendations

weather-parameters

Available weather and snow parameters from Open-Meteo API.

• URI: weather://parameters

• Format: JSON

• Content: Hourly/daily parameters with units and categories

Prompts

The server provides MCP prompts to guide LLM workflows:

ski-trip-weather

Guide for checking snow conditions and weather for ski trips.

• Arguments: resort, dates

• Workflow: Resort lookup → Snow conditions → Weather → Assessment

plan-outdoor-activity

Weather-aware outdoor activity planning workflow.

• Arguments: activity, location, timeframe

• Workflow: Activity sensitivity → Weather check → Suitability assessment

weather-aware-travel

Integration pattern for combining weather with journey planning.

• Arguments: destination, travel_dates, trip_type

• Workflow: Destination weather → Packing advice → Activity suggestions

Technology Stack

• Python 3.11+

• FastMCP - MCP server framework

• httpx - Async HTTP client

• Pydantic - Data validation

• structlog - Structured logging

• uv - Fast Python package manager

Prerequisites

• Python 3.11 or higher

• uv package manager

Installation

Install uv (if not already installed)

Windows (PowerShell):

powershell -c "irm https://astral.sh/uv/install.ps1 | iex"

macOS/Linux:

curl -LsSf https://astral.sh/uv/install.sh | sh

Install Dependencies

uv sync

This will install all required dependencies including FastMCP, httpx, pydantic, and testing tools.

Running Locally

Stdio Mode (for Claude Desktop)

uv run python -m open_meteo_mcp.server

Testing with MCP Inspector

npx @modelcontextprotocol/inspector uv run python -m open_meteo_mcp.server

MCP Integration

Claude Desktop Configuration

Add to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "open-meteo": {
      "command": "uv",
      "args": [
        "--directory",
        "C:\\Users\\YourUsername\\path\\to\\open-meteo-mcp",
        "run",
        "python",
        "-m",
        "open_meteo_mcp.server"
      ]
    }
  }
}

Note: Update the --directory path to match your local installation.

Development

Running Tests

# Run all tests
uv run pytest tests/ -v

# Run with coverage
uv run pytest tests/ --cov=open_meteo_mcp --cov-report=html

# Run specific test file
uv run pytest tests/test_models.py -v

Project Structure

open-meteo-mcp/
├── src/
│   └── open_meteo_mcp/
│       ├── __init__.py
│       ├── server.py          # FastMCP server with tools, resources, prompts
│       ├── client.py           # Open-Meteo API client
│       ├── models.py           # Pydantic models
│       ├── helpers.py          # Utility functions
│       └── data/               # JSON resource files
│           ├── weather-codes.json
...existing code...
│           └── weather-parameters.json
├── tests/
│   ├── test_models.py
│   ├── test_client.py
│   └── test_helpers.py
├── pyproject.toml              # Project configuration
└── .fastmcp/
    └── config.yaml             # FastMCP Cloud deployment config

Deployment

FastMCP Cloud

Deploy to FastMCP Cloud for remote access:

# Login to FastMCP Cloud
fastmcp login

# Deploy the server
fastmcp deploy

# Check deployment status
fastmcp status open-meteo-mcp

The server will be available at https://open-meteo-mcp.fastmcp.cloud

Example Usage

Once connected via MCP, you can ask:

Geocoding (NEW):

• "Find coordinates for Zurich"

• "Where is the Matterhorn?"

• "Search for Interlaken"

Weather Queries:

• "What's the weather in Bern, Switzerland?"

• "Show me the 7-day forecast for Zurich"

• "What's the UV index tomorrow?"

• "Chance of rain this weekend?"

Air Quality (NEW):

• "What's the air quality in Zurich?"

• "Pollen forecast for Bern?"

• "Is it safe to exercise outdoors today?"

Snow Conditions:

• "What are the snow conditions in Zermatt?"

• "Will it snow in the Alps this week?"

• "Wind conditions at Verbier?"

Ski Trip Planning (uses prompts + resources):

• "Plan a ski trip to Verbier this weekend"

• "Compare snow conditions across St. Moritz, Davos, and Zermatt"

Outdoor Activities (uses prompts):

• "I want to hike the Eiger Trail next week, what's the weather?"

• "Best days for cycling around Lake Geneva this week?"

• "Can I go hiking tomorrow? I have allergies" (checks weather + pollen)

Weather Codes

The API returns WMO weather codes. See docs/WEATHER_CODES.md for the complete reference.

Migration from Java

This is version 2.0 of the Open Meteo MCP server, migrated from Java/Spring Boot to Python/FastMCP for:

• Faster development and iteration

• Easier deployment with FastMCP Cloud

• Better integration with the MCP ecosystem

• Simpler codebase and dependencies

The Java version (v1.x) is archived in the java-v1 branch.

License

MIT License

Credits

Weather data provided by Open-Meteo - Free Open-Source Weather API.