Weather MCP Server

An MCP server that exposes US weather data from the National Weather Service (NWS) API. Built with FastMCP and httpx.

Requirements

• Python 3.13+
• uv (recommended) or another package manager

Setup

uv sync

Or with pip:

python -m venv .venv
source .venv/bin/activate
pip install -e .

Run the server

The server uses stdio transport (standard for local MCP clients):

uv run weather.py

Or:

python weather.py

Tools

Tool	Arguments	Description
get_alerts	state (two-letter US state code, e.g. CA, NY)	Active weather alerts for that state
get_forecast	latitude, longitude	Forecast for the next 5 periods at that location

Both tools call https://api.weather.gov and return human-readable text.

Use with Cursor / Claude Desktop

Add the server to your MCP client config. Example for Claude Desktop / Cursor:

{
  "mcpServers": {
    "weather": {
      "command": "uv",
      "args": ["--directory", "/absolute/path/to/weather", "run", "weather.py"]
    }
  }
}

Replace /absolute/path/to/weather with this project’s path. You can also point command at your Python interpreter and pass weather.py as the only arg.

Testing

Call the tools directly (no MCP client):

python test_direct.py

Other scripts in the repo exercise MCP stdio / JSON-RPC flows (test_mcp.py, test_mcp_simple.py, test_mcp_proper.py, test_mcp_integration.py, test_direct_io.py).

Project layout

weather.py   # FastMCP server and NWS tools
main.py      # Placeholder entrypoint
pyproject.toml

Notes

• Data is US-only (NWS coverage).
• Logs go to stderr so they do not interfere with stdio MCP messages.
• Forecasts are limited to the next 5 forecast periods.