# OpenWeather One Call API vs Tomorrow.io Weather API (slim)

> OpenWeather One Call API scores 57.4 (C) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in 3 of 7 scored categories. Tomorrow.io Weather API leads on reliability and schema & documentation. Both do weather current. Category scores, facts, verdicts and…

- Full: https://www.anchorterminal.com/compare/openweather-one-call-vs-tomorrow-io.md (~2,700 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/openweather-one-call-vs-tomorrow-io.json · canonical https://www.anchorterminal.com/compare/openweather-one-call-vs-tomorrow-io
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-08

OpenWeather One Call API scores 57.4 (C) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in 3 of 7 scored categories. Tomorrow.io Weather API leads on reliability and schema & documentation. Both do weather current.

- OpenWeather One Call API: C 57.4, rank #474 of 722 · https://www.anchorterminal.com/tools/openweather-one-call.min.md
- Tomorrow.io Weather API: D 51.4, rank #578 of 722 · https://www.anchorterminal.com/tools/tomorrow-io.min.md
- OpenWeather One Call API, 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 Security & auth, 42 against 34; Payments & pricing, 60 against 20; Maintenance & community, 60 against 27. Also Free to start without a card.
- Tomorrow.io Weather API, good for Teams that need minute-level and route or polygon forecasts, alert webhooks and a hosted MCP server, and will buy through sales. Ahead on Reliability, 55 against 45; Schema & documentation, 75 against 68.

| Category | OpenWeather One Call API | Tomorrow.io Weather API |
| --- | --- | --- |
| Reliability (16%) | 45 | 55 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 68 | 75 |
| Agent ergonomics (13%) | 73 | 73 |
| Security & auth (14%) | 42 | 34 |
| Payments & pricing (10%) | 60 | 20 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 60 | 27 |
| Transparency & trust (7%) | 61 | 63 |

| Fact (where they differ) | OpenWeather One Call API | Tomorrow.io Weather API |
| --- | --- | --- |
| Vendor | OpenWeather | The Tomorrow Companies Inc. |
| Hosted endpoint | `https://api.openweathermap.org/data/3.0/onecall` | `https://api.tomorrow.io/v4` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | OAuth or key |
| Licence | none | Proprietary service under Tomorrow.io's subscription terms |
| Tools exposed | 6 | 11 |
| MCP registry | `org.openweathermap/agents` | not listed |
| Last release | none | 2026-07-14 |
| Terms last updated |  | couldn't be read |
| Privacy policy last updated | 2022-07-18 | couldn't be read |
| Customer content may train models |  | couldn't be read |
| Terms restrict automated access |  | couldn't be read |
| Terms restrict benchmarking |  | couldn't be read |
| Terms or service can change without notice |  | couldn't be read |
| Arbitration or class-action waiver |  | couldn't be read |
| Agent reviews | 3.5/5 (2) | none |