congnguyen1905/mcp-weather-server

MCP Weather Server for n8n

A simple Model Context Protocol (MCP) server that provides weather information via OpenWeather API, designed to work with n8n's MCP client. This server uses the fastmcp library for easy MCP implementation.

Features

• 🌤️ Get current weather for any city
• 📅 Get 5-day weather forecast
• 📡 Server-Sent Events (SSE) for real-time communication
• 🔌 MCP protocol compatible
• 🚀 Simple and lightweight implementation

Setup

1. Install Dependencies

pip install -r requirements.txt

2. Configure OpenWeather API Key

You must set your OpenWeather API key as an environment variable:

export OPENWEATHER_API_KEY="your_api_key_here"

Note: The API key is required and the server will not start without it.

3. Run the Server

python mcp_openweather_server.py

The server will start on port 8000 using SSE (Server-Sent Events) transport.

Available Tools

The server provides two MCP tools:

1. get_current_weather

Get current weather conditions for a city.

Parameters:

• city (string, required): The name of the city (e.g., "London")
• units (string, optional): Temperature units - "metric" (Celsius), "imperial" (Fahrenheit), or "standard" (Kelvin). Defaults to "metric".

Returns:

• City name
• Temperature
• Feels like temperature
• Weather condition description
• Humidity percentage
• Wind speed
• Data source

2. get_weather_forecast

Get 5-day weather forecast for a city.

Parameters:

• city (string, required): The name of the city (e.g., "London")
• units (string, optional): Temperature units - "metric" (Celsius), "imperial" (Fahrenheit), or "standard" (Kelvin). Defaults to "metric".

Returns:

• City name
• Forecast data for the next 24 hours (3-hour intervals)
• Data source

n8n Integration

1. Install n8n MCP Client

In your n8n instance, install the MCP client node:

npm install n8n-nodes-mcp-client

2. Configure MCP Client Node

1. Add the MCP Client node to your workflow
2. Configure the connection:
   • Server URL: http://localhost:8000
   • Client ID: n8n (or any unique identifier)
   • Transport: SSE (Server-Sent Events)

3. Use the Weather Tools

The MCP client will automatically discover both available tools:

• get_current_weather - for current weather conditions
• get_weather_forecast - for weather forecasts

Technical Details

Architecture

• Framework: Uses fastmcp library for MCP implementation
• Transport: Server-Sent Events (SSE) over HTTP
• Port: 8000 (configurable in code)
• API: OpenWeatherMap API v2.5

Error Handling

The server includes error handling for:

• Missing API key
• Failed API requests
• Invalid responses

Dependencies

• fastmcp: MCP server implementation
• requests: HTTP client for API calls
• os: Environment variable handling

Troubleshooting

Common Issues

1. Missing API Key: Ensure OPENWEATHER_API_KEY environment variable is set
2. Port Already in Use: Change the port in the code if 8000 is occupied
3. API Rate Limits: OpenWeather API has rate limits for free tier accounts

Testing

You can test the server by running it and checking the console output. The server will show connection logs and any errors that occur.

Development

Adding New Tools

To add new tools, use the @mcp.tool decorator:

@mcp.tool
def your_tool_name(param1: str, param2: int = 0) -> dict:
    """
    Tool description.
    
    Args:
        param1: Description of param1
        param2: Description of param2
        
    Returns:
        Tool result
    """
    # Tool implementation
    return {"result": "success"}

Modifying Server Configuration

To change the server configuration, modify the mcp.run() call at the bottom of the file:

mcp.run(transport="sse", port=8000)

License

This project is open source and available under the MIT License.