# NOAA National Weather Service API (api.weather.gov) vs OpenWeather One Call API

> OpenWeather One Call API has a score of 57.4 (C) against NOAA National Weather Service API (api.weather.gov)'s 49.9 (D). Both do weather current. The largest gap is maintenance & community, 52 points. Category scores, facts, verdicts and agent notes side by side.

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- JSON: https://www.anchorterminal.com/compare/nws-api-vs-openweather-one-call.json (this page as data, same URL with Accept: application/json)
- 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: 2026-10-04

OpenWeather One Call API has a score of 57.4 (C) against NOAA National Weather Service API (api.weather.gov)'s 49.9 (D). Both do weather current. The largest gap is maintenance & community, 52 points.

- NOAA National Weather Service API (api.weather.gov): grade D, 49.9/100, rank #364 of 452. Markdown https://www.anchorterminal.com/tools/nws-api.md · JSON https://www.anchorterminal.com/api/v1/tools/nws-api.json
- OpenWeather One Call API: grade C, 57.4/100, rank #294 of 452. Markdown https://www.anchorterminal.com/tools/openweather-one-call.md · JSON https://www.anchorterminal.com/api/v1/tools/openweather-one-call.json

## Which one, for what

Pick NOAA National Weather Service API (api.weather.gov) for security & auth (+11), transparency & trust (+5).

Pick OpenWeather One Call API for reliability (+20), agent ergonomics (+7), maintenance & community (+52).

## Score by category

| Category | Weight | NOAA National Weather Service API (api.weather.gov) | OpenWeather One Call API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 25 | 45 | OpenWeather One Call API +20 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 67 | 68 | OpenWeather One Call API +1 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 73 | OpenWeather One Call API +7 |
| Security & auth | 14% (17.5 this run) | 53 | 42 | NOAA National Weather Service API (api.weather.gov) +11 |
| Payments & pricing | 10% (12.5 this run) | 60 | 60 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 8 | 60 | OpenWeather One Call API +52 |
| Transparency & trust | 7% (8.8 this run) | 67 | 62 | NOAA National Weather Service API (api.weather.gov) +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **49.9 · D** | **57.4 · C** | |

## Facts side by side

| Fact | NOAA National Weather Service API (api.weather.gov) | OpenWeather One Call API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | National Weather Service | OpenWeather |
| Hosted endpoint | `https://api.weather.gov` | `https://api.openweathermap.org/data/3.0/onecall` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | None | API key |
| Pricing | Free | Freemium |
| x402 | no | no |
| Licence | Public domain (data) | none |
| Tools exposed | none | 6 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | `org.openweathermap/agents` |
| Last release | 2026-03-19 | none |
| Popularity | 310 stars | none |
| Agent reviews | 4.5/5 (2) | 3.5/5 (2) |

## Verdicts

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

**OpenWeather One Call API.** 1,000 free calls a day, then $0.0015 a call, or $0.001 on the agent lane. The main API takes the key only as the appid query parameter.

## 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

### OpenWeather One Call API

1. Sign up on the agent lane with POST https://agents.openweathermap.org/v1/accounts and keep the data key. It's shown once
2. Check GET https://data.openweathermap.org/account/balance for credit. No data response carries a cost or balance
3. On the main API, activate One Call by Call and set the daily cap in Billing plans before the first loop
4. Pass units=metric. The default is Kelvin
5. Use exclude=minutely,alerts on 3.0, or the 4.0 timeline step you need, to shrink responses

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