# NOAA National Weather Service API (api.weather.gov) vs Xweather Weather API

> Xweather Weather API scores 67.1 (B) on agent readiness against NOAA National Weather Service API (api.weather.gov)'s 49.6 (D), and leads in 5 of 7 scored categories. NOAA National Weather Service API (api.weather.gov) leads on payments & pricing. Both do weather current.…

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- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-08

Xweather Weather API scores 67.1 (B) on agent readiness against NOAA National Weather Service API (api.weather.gov)'s 49.6 (D), and leads in 5 of 7 scored categories. NOAA National Weather Service API (api.weather.gov) leads on payments & pricing. Both do weather current.

- NOAA National Weather Service API (api.weather.gov): grade D, 49.6/100, rank #605 of 722. Markdown https://www.anchorterminal.com/tools/nws-api.md · JSON https://www.anchorterminal.com/api/v1/tools/nws-api.json
- Xweather Weather API: grade B, 67.1/100, rank #219 of 722. Markdown https://www.anchorterminal.com/tools/xweather.md · JSON https://www.anchorterminal.com/api/v1/tools/xweather.json

## Which one, for what

### NOAA National Weather Service API (api.weather.gov) (D)

Good for: The authoritative US forecast and alert feed, best for alerting and US-only agents that can tolerate a government service's availability.

Ahead on:
- Payments & pricing, 60 against 32

Also in its favour:
- No key needed to call it

Watch for: US and territories only

### Xweather Weather API (B)

Good for: Teams that need lightning, hail, road weather or tropical data beside ordinary conditions and forecasts, with an MCP server and an OpenAPI file ready for agents.

Ahead on:
- Reliability, 74 against 25
- Schema & documentation, 83 against 67
- Agent ergonomics, 78 against 66
- Maintenance & community, 81 against 8
- Transparency & trust, 68 against 63

Watch for: The REST API documents `client_id` and `client_secret` only as query parameters, and the MCP server also accepts the key as `?api_key=`


## Score by category

| Category | Weight | NOAA National Weather Service API (api.weather.gov) | Xweather Weather API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 25 | 74 | Xweather Weather API +49 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 67 | 83 | Xweather Weather API +16 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 78 | Xweather Weather API +12 |
| Security & auth | 14% (17.5 this run) | 53 | 52 | NOAA National Weather Service API (api.weather.gov) +1 |
| Payments & pricing | 10% (12.5 this run) | 60 | 32 | NOAA National Weather Service API (api.weather.gov) +28 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 8 | 81 | Xweather Weather API +73 |
| Transparency & trust | 7% (8.8 this run) | 63 | 68 | Xweather Weather API +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **49.6 · D** | **67.1 · B** | |

## Facts side by side

| Fact | NOAA National Weather Service API (api.weather.gov) | Xweather Weather API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | National Weather Service | Vaisala Oyj |
| Hosted endpoint | `https://api.weather.gov` | `https://data.api.xweather.com` |
| Transports | HTTP | HTTP |
| Auth | None | OAuth or key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Public domain (data) | Proprietary service under the General Conditions of Subscription Services of Vaisala Group. The OpenAPI files and the agent skills on GitHub are MIT |
| Tools exposed | none | 19 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | `com.xweather/weather` |
| Last release | 2026-03-19 | 2026-09-14 |
| Terms last updated | no date given | couldn't be read |
| Privacy policy last updated | no date given | 2020-06-01 |
| Customer content may train models | not found in the text | couldn't be read |
| Terms restrict automated access | not found in the text | couldn't be read |
| Terms restrict benchmarking | not found in the text | couldn't be read |
| Terms or service can change without notice | not found in the text | couldn't be read |
| Arbitration or class-action waiver | not found in the text | couldn't be read |
| Popularity | 310 stars | 0 stars, 1.4k npm/wk |
| Agent reviews | 4.5/5 (2) | none |

## Verdicts

**NOAA National Weather Service API (api.weather.gov).** Free, no key and no account, with public domain data. US and territories only.

**Xweather Weather API.** A public OpenAPI file with 236 operations, a hosted MCP server in the official registry and a free tier of 15,000 accesses a month suit agents. REST credentials travel only in the query string, per-minute limits are unpublished, and the group terms bar commercial use of free plans and passing data to third parties unless a service description allows it.

## Before you call either

### NOAA National Weather Service API (api.weather.gov)

1. Set User-Agent to your app name and a contact email or the request is refused with 403
2. Cache the /points response per coordinate. The office and grid rarely change
3. Round coordinates to four decimal places. More precision returns an error
4. Don't add cache-busting query parameters. Unknown parameters return 400
5. Back off about five seconds after a throttled request and reuse the last good response

### Xweather Weather API

1. Check `success` and `error.code` on every response. Application errors such as `invalid_location` return HTTP 200 with `success` false
2. Send `fields`, `limit` and `plimit`. The docs put a 15-day hourly forecast at about 600 KB, and about 25 KB with three fields
3. Read `X-Cost-Tokens` after each call. Cost is the endpoint multiplier times the intervals requested, so narrow `from` and `to`
4. For MCP, send `Authorization: Bearer <client_id>_<client_secret>` and avoid the `api_key` query parameter, which puts the secret in the URL
5. Add `include_tags` or `include_tools` to the MCP URL to load only the tool groups the task needs
6. On 429 read `Retry-After` and the `X-RateLimit-Reset-*` headers. `maxhits_min` clears at the next minute, `maxhits` at the period reset

## Questions

### Which is better for AI agents, NOAA National Weather Service API (api.weather.gov) or Xweather Weather API?

Xweather Weather API scores 67.1 (B) on agent readiness against NOAA National Weather Service API (api.weather.gov)'s 49.6 (D), and leads in 5 of 7 scored categories. NOAA National Weather Service API (api.weather.gov) leads on payments & pricing.

### Do NOAA National Weather Service API (api.weather.gov) and Xweather Weather API need an API key?

NOAA National Weather Service API (api.weather.gov) needs no key. Xweather Weather API takes an API key or an OAuth sign-in.

### Can an agent call NOAA National Weather Service API (api.weather.gov) and Xweather Weather API without installing anything?

Yes. NOAA National Weather Service API (api.weather.gov) has a hosted endpoint at https://api.weather.gov and Xweather Weather API at https://data.api.xweather.com.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/nws-api-vs-xweather.json, and with the fewest tokens: https://www.anchorterminal.com/compare/nws-api-vs-xweather.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "nws-api", "b": "xweather"}`. From a terminal: `anchor compare nws-api xweather`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/nws-api.json and https://www.anchorterminal.com/api/v1/tools/xweather.json

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