# Tomorrow.io Weather API vs Xweather Weather API

> Xweather Weather API scores 67.1 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category. Both do weather current. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/tomorrow-io-vs-xweather
- Markdown: https://www.anchorterminal.com/compare/tomorrow-io-vs-xweather.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/tomorrow-io-vs-xweather.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/tomorrow-io-vs-xweather.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: 2026-10-08

Xweather Weather API scores 67.1 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category. 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
- 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

### 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.

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

### 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 55
- Schema & documentation, 83 against 75
- Agent ergonomics, 78 against 73
- Security & auth, 52 against 34
- Payments & pricing, 32 against 20
- Maintenance & community, 81 against 27
- 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 | Tomorrow.io Weather API | Xweather Weather API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 55 | 74 | Xweather Weather API +19 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 75 | 83 | Xweather Weather API +8 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 78 | Xweather Weather API +5 |
| Security & auth | 14% (17.5 this run) | 34 | 52 | Xweather Weather API +18 |
| Payments & pricing | 10% (12.5 this run) | 20 | 32 | Xweather Weather API +12 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 27 | 81 | Xweather Weather API +54 |
| Transparency & trust | 7% (8.8 this run) | 63 | 68 | Xweather Weather API +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **51.4 · D** | **67.1 · B** | |

## Facts side by side

| Fact | Tomorrow.io Weather API | Xweather Weather API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | The Tomorrow Companies Inc. | Vaisala Oyj |
| Hosted endpoint | `https://api.tomorrow.io/v4` | `https://data.api.xweather.com` |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Proprietary service under Tomorrow.io's subscription terms | 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 | 11 | 19 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | `com.xweather/weather` |
| Last release | 2026-07-14 | 2026-09-14 |
| Terms last updated | couldn't be read | couldn't be read |
| Privacy policy last updated | couldn't be read | 2020-06-01 |
| Customer content may train models | couldn't be read | couldn't be read |
| Terms restrict automated access | couldn't be read | couldn't be read |
| Terms restrict benchmarking | couldn't be read | couldn't be read |
| Terms or service can change without notice | couldn't be read | couldn't be read |
| Arbitration or class-action waiver | couldn't be read | couldn't be read |
| Popularity | none | 0 stars, 1.4k npm/wk |

## 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.

**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

### 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

### 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, Tomorrow.io Weather API or Xweather Weather API?

Xweather Weather API scores 67.1 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category.

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

Both take an API key or an OAuth sign-in.

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

Yes. Tomorrow.io Weather API has a hosted endpoint at https://api.tomorrow.io/v4 and Xweather Weather API at https://data.api.xweather.com.


## For agents

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

## Other comparisons with Tomorrow.io Weather API or Xweather Weather API

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