Thx93/mcp-weather-server

A minimal Model Context Protocol server that
exposes US weather data from the
National Weather Service API
as two read-only tools.
The NWS API is free, keyless and US-only, so this server needs no credentials and
no account to run.
| Tool | Input | Returns |
| get-alerts | state — two-letter code, e.g. CA | Active weather alerts for that state |
| get-forecast | latitude, longitude | The next five forecast periods for that point |
Both tools are annotated readOnlyHint: true and destructiveHint: false, so a
host that respects tool annotations can invoke them without asking first. Both
reach out to api.weather.gov and are marked openWorldHint: true for that reason.
## Use it hosted, paid per call
Running it yourself costs nothing. There is also a hosted version, paid per call
in USDC on Base over x402, for agents that would rather not carry a Node process
and a data layer:
https://agent-evidence.thx93.dev/weather/mcp
It serves the same two tools, with the same output schemas and the same null
fallbacks, plus a free health tool and free tools/list so the service can be
discovered and probed before paying. Discovery is free; a tools/call for
get-alerts or get-forecast returns 402 with the price. Both are declared
read-only, so a host that respects annotations will not ask twice.
The server.json in this repository advertises that remote, so an MCP client can
install it by registry name rather than by cloning anything.
## Prerequisites
Node.js 24+
npm
## Build, test and run
bash
npm install
npm test # builds, then runs the suite
npm run build # compile only
node build/index.js
The suite drives the real server over InMemoryTransport with the NWS API stubbed,
so npm test touches no network and needs no credentials. It covers tool
discovery and annotations, the get-alerts and get-forecast data paths, the
fallbacks for fields the NWS sends as null, the failure contract, and input
validation.
Running node build/index.js speaks the MCP protocol over stdio: it prints to
stderr and waits for a client on stdin, so it is meant to be launched by a host
rather than by hand.
## Adding it to a client
Most MCP hosts use the same three-line shape:
json
"mcpServers": {
"weather": {
"command": "node",
"args": ["/absolute/path/to/mcp-weather-server/build/index.js"]
Or straight from npm — published 2026-10-19:
bash
npx -y @thx93/mcp-weather-server
Or, equivalently, as a client config entry:
json
"mcpServers": {
"weather": { "command": "npx", "args": ["-y", "@thx93/mcp-weather-server"] }
Or straight from the repository, with no registry account needed:
bash
npm install github:Thx93/mcp-weather-server
That path works because prepare builds the server during the install; build/ is
not committed, so without it the bin would point at a file that does not exist. It
was verified end to end — install from GitHub, then speak MCP to the result, and both
tools list with object output schemas.
## Verified against the source
The tools return the National Weather Service's own data, so correctness is
checkable rather than asserted. On 2026-10-19, api.weather.gov reported one active
alert for TX and a paid call to the hosted get-alerts returned exactly one -
Event: Flood Advisory - for the same state.