# nws-weather-mcp-server [Health: Active]
**Category:** 💻 Developer Tools
**Repository:** https://github.com/cyanheads/nws-weather-mcp-server
**GitHub Stars:** 1
**Views:** 0
**Installs:** 0
**Upvotes:** 0
**Directory Page:** https://allmcps.com/mcp/nws-weather-mcp-server
## Description
Real-time US weather data via National Weather Service API. Forecasts, alerts, and observations.
## Claude Desktop Quick Installation
Install path detected from listing signals. Uses `bunx` (confidence: high):
```json
"mcpServers": {
"nws-weather-mcp-server": {
"command": "bunx",
"args": ["@cyanheads/nws-weather-mcp-server@latest"]
}
}
```
## Documentation & README
@cyanheads/nws-weather-mcp-server
Get US weather forecasts, active alerts, and current observations via the National Weather Service API. STDIO or Streamable HTTP.
7 Tools • 1 Resource
[](./CHANGELOG.md) [](./LICENSE) [](https://github.com/users/cyanheads/packages/container/package/nws-weather-mcp-server) [](https://modelcontextprotocol.io/) [](https://www.npmjs.com/package/@cyanheads/nws-weather-mcp-server) [](https://www.typescriptlang.org/) [](https://bun.sh/)
[](https://github.com/cyanheads/nws-weather-mcp-server/releases/latest/download/nws-weather-mcp-server.mcpb) [](https://cursor.com/en/install-mcp?name=nws-weather-mcp-server&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyIteSIsIkBjeWFuaGVhZHMvbndzLXdlYXRoZXItbWNwLXNlcnZlciJdfQ==) [](https://vscode.dev/redirect?url=vscode:mcp/install?%7B%22name%22%3A%22nws-weather-mcp-server%22%2C%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22-y%22%2C%22%40cyanheads/nws-weather-mcp-server%22%5D%7D)
[](https://www.npmjs.com/package/@cyanheads/mcp-ts-core)
**Public Hosted Server:** [https://nws.caseyjhand.com/mcp](https://nws.caseyjhand.com/mcp)
---
## Tools
Seven tools for real-time US weather data:
| Tool | Description |
|:----------|:------------|
| `nws_get_forecast` | 7-day or hourly forecast for coordinates. Resolves NWS grid internally. |
| `nws_search_alerts` | Active weather alerts filtered by area, point, zone, event, severity, urgency, certainty, and status. |
| `nws_get_observations` | Current conditions by coordinates (nearest station) or station ID. |
| `nws_find_stations` | Nearby observation stations sorted by distance with bearing. |
| `nws_list_alert_types` | All valid alert event type names for filter discovery. |
| `nws_get_office_discussion` | Latest narrative product (AFD, HWO, ZFP, SPS) from a Weather Forecast Office. |
| `nws_get_zone_forecast` | Text forecast periods for a public NWS forecast zone. |
### `nws_get_forecast`
Get the weather forecast for a US location.
- Default returns named 12-hour periods (14 total, ~7 days)
- Hourly mode returns 48 one-hour periods per page with dewpoint and humidity — the upstream feed carries ~156, and the pre-page total (`totalCount`, against this page's `shown`) plus a truncation notice are surfaced in the enrichment block
- Pass the returned `nextCursor` back as `cursor` to reach the remaining periods; it is omitted on the last page
- Coordinates resolve to NWS grid internally via `/points` endpoint
- Formatted timestamps use the resolved local time zone
- Returns forecast zone and county zone codes for chaining into `nws_search_alerts`
---
### `nws_search_alerts`
Search active weather alerts with flexible filtering.
- Filter by area (state/territory/marine codes), point (lat,lon), zone, land/marine `region_type`, marine `region` groups, event type, severity, urgency, certainty, or status
- `area`, `point`, `zone`, `region_type`, and `region` are mutually exclusive; specify at most one location filter
- National search when no filters provided
- A filter provided with no usable value — a blank `area`/`point`/`zone`, or an empty `event`/`severity`/`urgency`/`certainty`/`region` array — is rejected rather than dropped, so a search never silently widens to national results
- Each `affectedZones` entry carries its NWS zone `type` (`forecast`, `county`, or `fire`) alongside the `code`, so callers can tell which codes chain into `nws_get_zone_forecast`
- Alerts include the CAP message lifecycle — `sent`, `effective`, `status`, `messageType`, and the prior messages an update `references` — distinct from the hazard's own `onset`/`ends`
- Event matching is case-insensitive and partial, so `"tornado"` matches both watches and warnings
- `status` defaults to live `Actual` alerts, but can be set to `Exercise`, `System`, `Test`, or `Draft`
- Optional `limit` (1–25, default 25) sizes the page; `totalCount` reports the full match count and `shown` the size of this page, with a truncation notice and guidance to narrow filters
- Alerts NWS repeats verbatim within one fetch are collapsed on `id`, so `totalCount` counts distinct alerts and a duplicate never straddles a page boundary
- Pass the returned `nextCursor` back as `cursor` to reach matches beyond the page. Consecutive pages are contiguous within one response only — every call re-fetches `/alerts/active`, and that set changes continuously as alerts are issued and expire
- Validates area, point, and zone locally before the API call — malformed values fail fast as `invalid_area_code`, `invalid_point`, or `invalid_zone` instead of leaking a raw upstream 400
---
### `nws_get_observations`
Current measured conditions from a weather station.
- Look up by coordinates (finds nearest station) or station ID directly
- A blank or whitespace-only `station_id` is rejected rather than dropped, so coordinates never silently answer for a station that was asked for by name
- Coordinate lookups choose the nearest station from the candidates returned by NWS
- Dual-unit display: F/C, mph/km/h, inHg/hPa, mi/km
- Observation timestamps use the station's local time zone when available
- Warns when most measurements are unavailable from a station
---
### `nws_find_stations`
Discover nearby observation stations.
- Sorted by haversine distance from query point
- Returns distance (km) and compass bearing
- Includes zone codes, elevation, time zone
- Optional `limit` (1–50, default 10) sizes the page; `totalCount` reports every station near the point and holds steady across pages, while `shown` is the size of this page
- Pass the returned `nextCursor` back as `cursor` to reach stations beyond the page; it is omitted on the last page
- Useful for finding station IDs for `nws_get_observations`
---
### `nws_list_alert_types`
List all valid NWS alert event type names.
- Returns the full set of event types the NWS API recognizes (e.g., "Tornado Warning", "Heat Advisory")
- Use to discover valid values for the `event` filter in `nws_search_alerts`
---
### `nws_get_office_discussion`
Get the latest narrative product from a Weather Forecast Office (WFO).
- `office`: 3-letter WFO code (e.g., `SEW` for Seattle) — returned as the `office` field by `nws_get_forecast`
- `product_type`: `AFD` (Area Forecast Discussion, default), `HWO` (Hazardous Weather Outlook), `ZFP` (Zone Forecast Product), `SPS` (Special Weather Statement)
- Two-hop fetch: lists products by office/type (newest first), then retrieves full product text
- Returns `productText` plus `issuanceTime`, `issuingOffice`, `productName`, `productCode`, `wmoCollectiveId`
- Unknown office returns a clear error with recovery instructions (the NWS API returns HTTP 200 with an empty list, not a 404)
---
### `nws_get_zone_forecast`
Get the text forecast for a public NWS forecast zone.
- `zone_id`: forecast zone code (e.g., `WAZ315`) — returned by `nws_get_forecast` (`forecastZone`), `nws_find_stations` (`forecastZone` column), and `nws_search_alerts` (the `code` of an `affectedZones` entry with `type: "forecast"`)
- Returns named periods (e.g., "Today", "Tonight", "Monday") with narrative text from local forecasters
- Completes the alert-to-forecast chain: look up alert zones, then retrieve zone forecasts
- County (`XXC###`) and fire zone codes are not supported here — NWS publishes no text forecast for them. They remain valid values for the `zone` filter on `nws_search_alerts`
## Resources
| URI Pattern | Description |
|:------------|:------------|
| `nws://alert-types` | Static list of all valid NWS alert event type names. |
## Features
Built on [`@cyanheads/mcp-ts-core`](https://github.com/cyanheads/mcp-ts-core):
- Declarative tool definitions — single file per tool, framework handles registration and validation
- Unified error handling across all tools
- Pluggable auth (`none`, `jwt`, `oauth`)
- Swappable storage backends: `in-memory`, `filesystem`, `Supabase`, `Cloudflare KV/R2/D1`
- Structured logging with optional OpenTelemetry tracing
- Runs locally (stdio/HTTP) or on Cloudflare Workers from the same codebase
NWS-specific:
- Zero-auth access to the NWS API — no API keys required
- Automatic coordinate-to-grid resolution with caching (1h TTL)
- Request timeouts plus retry/backoff for transient NWS API failures
- Dual-unit display for observations (F/C, mph/km/h, inHg/hPa, mi/km)
- Continental US, Alaska, Hawaii, and US territories coverage
## Getting started
### Public Hosted Instance
A public instance is available at `https://nws.caseyjhand.com/mcp` — no installation required. Point any MCP client at it via Streamable HTTP:
```json
{
"mcpServers": {
"nws-weather-mcp-server": {
"type": "streamable-http",
"url": "https://nws.caseyjhand.com/mcp"
}
}
}
```
### Self-Hosted / Local
Add the following to your MCP client configuration file.
```json
{
"mcpServers": {
"nws-weather-mcp-server": {
"type": "stdio",
"command": "bunx",
"args": ["@cyanheads/nws-weather-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with npx (no Bun required):
```json
{
"mcpServers": {
"nws-weather-mcp-server": {
"type": "stdio",
"command": "npx",
"args": ["-y", "@cyanheads/nws-weather-mcp-server@latest"],
"env": {
"MCP_TRANSPORT_TYPE": "stdio",
"MCP_LOG_LEVEL": "info"
}
}
}
}
```
Or with Docker:
```json
{
"mcpServers": {
"nws-weather-mcp-server": {
"type": "stdio",
"command": "docker",
"args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/nws-weather-mcp-server:latest"]
}
}
}
```
For Streamable HTTP, set the transport and start the server:
```sh
MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp
```
### Prerequisites
- [Node.js v24+](https://nodejs.org/) or [Bun v1.3+](https://bun.sh/)
### Installation
1. **Clone the repository:**
```sh
git clone https://github.com/cyanheads/nws-weather-mcp-server.git
```
2. **Navigate into the directory:**
```sh
cd nws-weather-mcp-server
```
3. **Install dependencies:**
```sh
bun install
```
## Configuration
| Variable | Description | Default |
|:---------|:------------|:--------|
| `NWS_USER_AGENT` | User-Agent for NWS API requests. The API requires this header. | `(nws-weather-mcp-server, ...)` |
| `MCP_TRANSPORT_TYPE` | Transport: `stdio` or `http`. | `stdio` |
| `MCP_HTTP_PORT` | Port for HTTP server. | `3010` |
| `MCP_HTTP_HOST` | Hostname for HTTP server. | `127.0.0.1` |
| `MCP_SESSION_MODE` | HTTP session mode: `stateful`, `stateless`, or `auto`. | `stateless` |
| `MCP_LOG_LEVEL` | Log level: `debug`, `info`, `notice`, `warning`, `error`. | `info` |
See [`.env.example`](https://github.com/cyanheads/nws-weather-mcp-server/blob/HEAD/.env.example) for the full list including auth, storage, and OpenTelemetry options.
## Running the server
### Local development
- **Build and run the production version:**
```sh
# One-time build
bun run rebuild
# Run the built server
bun run start:http
# or
bun run start:stdio
```
- **Run checks and tests:**
```sh
bun run devcheck # Lints, formats, type-checks
bun run test # Runs test suite
```
## Project structure
| Directory | Purpose |
|:----------|:--------|
| `src/mcp-server/tools/definitions/` | Tool definitions (`*.tool.ts`). |
| `src/mcp-server/resources/definitions/` | Resource definitions (`*.resource.ts`). |
| `src/services/nws/` | NWS API client and response types. |
| `src/config/` | Environment variable parsing and validation with Zod. |
## Development guide
See [`CLAUDE.md`](https://github.com/cyanheads/nws-weather-mcp-server/blob/HEAD/CLAUDE.md) for development guidelines and architectural rules. The short version:
- Handlers throw, framework catches — no `try/catch` in tool logic
- Use `ctx.log` for domain-specific logging, `ctx.state` for storage
- Add new tools/resources to the barrel exports and the `createApp()` arrays in `src/index.ts`
## Contributing
Issues and pull requests are welcome. Run checks before submitting:
```sh
bun run devcheck
bun run test
```
## License
Apache-2.0 — see [LICENSE](https://github.com/cyanheads/nws-weather-mcp-server/blob/HEAD/LICENSE) for details.