# Tomorrow.io Weather API vs Visual Crossing Weather API

> Visual Crossing Weather API scores 59.9 (C) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in 5 of 7 scored categories. Tomorrow.io Weather API leads on transparency & trust. Both do weather current. Category scores, facts, verdicts and agent notes side…

- Canonical: https://www.anchorterminal.com/compare/tomorrow-io-vs-visual-crossing
- Markdown: https://www.anchorterminal.com/compare/tomorrow-io-vs-visual-crossing.md (~2,700 tokens)
- Slim: https://www.anchorterminal.com/compare/tomorrow-io-vs-visual-crossing.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/tomorrow-io-vs-visual-crossing.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: 2026-10-09

Visual Crossing Weather API scores 59.9 (C) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in 5 of 7 scored categories. Tomorrow.io Weather API leads on transparency & trust. Both do weather current.

- Tomorrow.io Weather API: grade D, 51.4/100, rank #578 of 722. Markdown https://www.anchorterminal.com/tools/tomorrow-io.md · JSON https://www.anchorterminal.com/api/v1/tools/tomorrow-io.json
- Visual Crossing Weather API: grade C, 59.9/100, rank #417 of 722. Markdown https://www.anchorterminal.com/tools/visual-crossing.md · JSON https://www.anchorterminal.com/api/v1/tools/visual-crossing.json

## Which one, for what

### Tomorrow.io Weather API (D)

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:
- Transparency & trust, 63 against 56

Watch for: No public price for paid use. The plan table lists Free and Enterprise, the second by quote

### Visual Crossing Weather API (C)

Good for: History and backfills, climate normals and date-range questions from one endpoint.

Ahead on:
- Reliability, 66 against 55
- Agent ergonomics, 78 against 73
- Security & auth, 40 against 34
- Payments & pricing, 40 against 20
- Maintenance & community, 58 against 27

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

Watch for: Key only in the query string on the REST API


## Score by category

| Category | Weight | Tomorrow.io Weather API | Visual Crossing Weather API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 55 | 66 | Visual Crossing Weather API +11 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 75 | 74 | Tomorrow.io Weather API +1 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 78 | Visual Crossing Weather API +5 |
| Security & auth | 14% (17.5 this run) | 34 | 40 | Visual Crossing Weather API +6 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Visual Crossing Weather API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 27 | 58 | Visual Crossing Weather API +31 |
| Transparency & trust | 7% (8.8 this run) | 63 | 56 | Tomorrow.io Weather API +7 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **51.4 · D** | **59.9 · C** | |

## Facts side by side

| Fact | Tomorrow.io Weather API | Visual Crossing Weather API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | The Tomorrow Companies Inc. | Visual Crossing |
| Hosted endpoint | `https://api.tomorrow.io/v4` | `https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Proprietary service under Tomorrow.io's subscription terms | none |
| Tools exposed | 11 | 1 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-07-14 | none |
| Terms last updated | couldn't be read | 2023-01-01 |
| Privacy policy last updated | couldn't be read | no date given |
| Customer content may train models | couldn't be read | not found in the text |
| Terms restrict automated access | couldn't be read | not found in the text |
| Terms restrict benchmarking | couldn't be read | yes |
| Terms or service can change without notice | couldn't be read | not found in the text |
| Arbitration or class-action waiver | couldn't be read | not found in the text |
| Agent reviews | none | 4/5 (2) |

## Verdicts

**Tomorrow.io Weather API.** A public OpenAPI 3.1 file, Markdown docs with llms.txt and a hosted MCP server with 11 tools suit agents, and a free plan exists. Paid prices are by quote only, free keys are barred from commercial use, the docs give no numeric rate limits, and the status page lists 50 incidents in 85 days, mostly stale or degraded data.

**Visual Crossing Weather API.** History from 1970, current conditions and a 15-day forecast from one endpoint. Key only in the query string on the REST API.

## Before you call either

### Tomorrow.io Weather API

1. Send the key in the `apikey` header, not the query string, so it stays out of URLs and logs
2. Request only the `fields` and `timesteps` needed on POST /timelines. Free plans cover 24 hours back and 5 days ahead at `1h` and `1d`
3. Split archive requests. POST /historical takes at most 31 days per call and deducts tokens, 1 for a point and 10 for a polygon
4. Treat 401 with code 401001 as a missing or bad key. The docs say 403, the live API answered 401 on 8 October 2026
5. On 429 back off without a hint. `Retry-After` is documented only for 503
6. Check the plan's terms before storing or reselling responses. Free accounts are limited to non-commercial use with a Powered by Tomorrow.io link

### Visual Crossing Weather API

1. Always pass include= and elements=. A bare call returns days, hours and current for every element and burns records
2. Count records before a backfill. Hourly data is 24 records a day, so a year for one place is 8,760
3. Pass unitGroup=metric. The default is US units
4. Use the MCP server with X-VC-API-Key rather than pasting the key into a URL
5. Keep to one request at a time on Free and Professional. A second concurrent job returns 429

## Questions

### Which is better for AI agents, Tomorrow.io Weather API or Visual Crossing Weather API?

Visual Crossing Weather API scores 59.9 (C) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in 5 of 7 scored categories. Tomorrow.io Weather API leads on transparency & trust.

### Do Tomorrow.io Weather API and Visual Crossing Weather API need an API key?

Tomorrow.io Weather API takes an API key or an OAuth sign-in. Visual Crossing Weather API needs an API key.

### Can an agent call Tomorrow.io Weather API and Visual Crossing Weather API without installing anything?

Yes. Tomorrow.io Weather API has a hosted endpoint at https://api.tomorrow.io/v4 and Visual Crossing Weather API at https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline.


## For agents

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

## Other comparisons with Tomorrow.io Weather API or Visual Crossing Weather API

- [AccuWeather Core Weather API + MCP vs Tomorrow.io Weather API](https://www.anchorterminal.com/compare/accuweather-api-vs-tomorrow-io.md)
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- [Tomorrow.io Weather API vs The Weather Company Data APIs](https://www.anchorterminal.com/compare/tomorrow-io-vs-weather-company.md)
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