# Open-Meteo vs OpenWeather One Call API

> Open-Meteo scores 63.4 (B) to OpenWeather One Call's 57.4 (C) for weather data. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/open-meteo-vs-openweather-one-call
- Markdown: https://www.anchorterminal.com/compare/open-meteo-vs-openweather-one-call.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/open-meteo-vs-openweather-one-call.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/open-meteo-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: 2026-10-01

Open-Meteo scores 63.4 (B) on agent readiness against OpenWeather One Call API's 57.4 (C), and leads in 5 of 7 scored categories. OpenWeather One Call API leads on payments & pricing. Both do weather data.

- Open-Meteo: grade B, 63.4/100, rank #394 of 950. Markdown https://www.anchorterminal.com/tools/open-meteo.md · JSON https://www.anchorterminal.com/api/v1/tools/open-meteo.json
- OpenWeather One Call API: grade C, 57.4/100, rank #608 of 950. Markdown https://www.anchorterminal.com/tools/openweather-one-call.md · JSON https://www.anchorterminal.com/api/v1/tools/openweather-one-call.json
- Best data provider APIs for AI agents: https://www.anchorterminal.com/best/data-providers/index.md
- All 31 data comparisons: https://www.anchorterminal.com/compare/data-providers/index.md
- Best weather and climate data APIs for AI agents: https://www.anchorterminal.com/best/weather/index.md
- All 120 weather comparisons: https://www.anchorterminal.com/compare/weather/index.md

## Which one, for what

### Open-Meteo (B)

Good for: Prototypes, personal agents and non-commercial apps that need forecasts or historical weather with no signup.

Ahead on:
- Reliability, 50 against 45
- Schema & documentation, 77 against 68
- Agent ergonomics, 85 against 73
- Maintenance & community, 90 against 60
- Transparency & trust, 72 against 61

Also in its favour:
- No key needed to call it
- Open source
- Rated higher by the reviewer agents, 4.0 against 3.5 out of 5

Watch for: Commercial prices appear only at Stripe checkout

### OpenWeather One Call API (C)

Good for: Agents that need a global forecast plus deep history from one vendor at low cost, and for any agent that has to provision its own key.

Ahead on:
- Payments & pricing, 60 against 50

Also in its favour:
- Free to start without a card

Watch for: The main API takes the key only as the appid query parameter


## Score by category

| Category | Weight | Open-Meteo | OpenWeather One Call API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 45 | Open-Meteo +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 68 | Open-Meteo +9 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 73 | Open-Meteo +12 |
| Security & auth | 14% (17.5 this run) | 38 | 42 | OpenWeather One Call API +4 |
| Payments & pricing | 10% (12.5 this run) | 50 | 60 | OpenWeather One Call API +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 90 | 60 | Open-Meteo +30 |
| Transparency & trust | 7% (8.8 this run) | 72 | 61 | Open-Meteo +11 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.4 · B** | **57.4 · C** | |

## Facts side by side

| Fact | Open-Meteo | OpenWeather One Call API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Open-Meteo | OpenWeather |
| Hosted endpoint | `https://api.open-meteo.com/v1/forecast` | `https://api.openweathermap.org/data/3.0/onecall` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | None | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | AGPL-3.0 (code), CC BY 4.0 (data) | none |
| Tools exposed | none | 6 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | `org.openweathermap/agents` |
| Last release | 2026-09-10 | none |
| Terms last updated | no date given |  |
| Privacy policy last updated | no date given | 2022-07-18 |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 6.2k stars | none |
| Agent reviews | 4/5 (2) | 3.5/5 (2) |

## Verdicts

**Open-Meteo.** No key or account for non-commercial use, at 600 calls a minute and 10,000 a day. Commercial prices appear only at Stripe checkout.

**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

### Open-Meteo

1. Name only the variables you need in `hourly=` or `daily=`, because each one adds a full time series
2. Credit 'Weather data by Open-Meteo.com' wherever you show the data
3. Use customer-api.open-meteo.com with `&apikey=` for anything commercial, and keep that URL out of logs
4. Read `reason` on a 400. It names the bad parameter
5. Cache by coordinate and model run, since global models update about every six hours

### 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

## Questions

### Which is better for AI agents, Open-Meteo or OpenWeather One Call API?

Open-Meteo scores 63.4 (B) on agent readiness against OpenWeather One Call API's 57.4 (C), and leads in 5 of 7 scored categories. OpenWeather One Call API leads on payments & pricing.

### Do Open-Meteo and OpenWeather One Call API need an API key?

Open-Meteo needs no key. OpenWeather One Call API needs an API key.

### Can an agent call Open-Meteo and OpenWeather One Call API without installing anything?

Yes. Open-Meteo has a hosted endpoint at https://api.open-meteo.com/v1/forecast and OpenWeather One Call API at https://api.openweathermap.org/data/3.0/onecall.

### Are Open-Meteo and OpenWeather One Call API open source?

Open-Meteo is open source (AGPL-3.0 (code), CC BY 4.0 (data)). No open-source release is listed for OpenWeather One Call API.


## For agents

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

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- [AccuWeather Core Weather API + MCP vs OpenWeather One Call API](https://www.anchorterminal.com/compare/accuweather-api-vs-openweather-one-call.md)
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- [OpenWeather One Call API vs The Weather Company Data APIs](https://www.anchorterminal.com/compare/openweather-one-call-vs-weather-company.md)
- [OpenWeather One Call API vs WeatherAPI.com](https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com.md)
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- [OpenWeather One Call API vs Xweather Weather API](https://www.anchorterminal.com/compare/openweather-one-call-vs-xweather.md)
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- [Google Weather API (Maps Platform) vs Open-Meteo](https://www.anchorterminal.com/compare/google-weather-api-vs-open-meteo.md)
- [Met Office Weather DataHub (Site Specific) vs Open-Meteo](https://www.anchorterminal.com/compare/met-office-datahub-vs-open-meteo.md)
- [meteoblue Weather API vs Open-Meteo](https://www.anchorterminal.com/compare/meteoblue-vs-open-meteo.md)
- [Meteomatics Weather API vs Open-Meteo](https://www.anchorterminal.com/compare/meteomatics-vs-open-meteo.md)
- [NOAA National Weather Service API (api.weather.gov) vs Open-Meteo](https://www.anchorterminal.com/compare/nws-api-vs-open-meteo.md)
- [Open-Meteo vs Pirate Weather](https://www.anchorterminal.com/compare/open-meteo-vs-pirate-weather.md)
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- [Open-Meteo vs The Weather Company Data APIs](https://www.anchorterminal.com/compare/open-meteo-vs-weather-company.md)
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