# Pirate Weather vs Tomorrow.io Weather API

> Pirate Weather scores 65.9 (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/pirate-weather-vs-tomorrow-io
- Markdown: https://www.anchorterminal.com/compare/pirate-weather-vs-tomorrow-io.md (~2,650 tokens)
- Slim: https://www.anchorterminal.com/compare/pirate-weather-vs-tomorrow-io.min.md (~580 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/pirate-weather-vs-tomorrow-io.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

Pirate Weather scores 65.9 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category. Both do weather current.

- Pirate Weather: grade B, 65.9/100, rank #249 of 722. Markdown https://www.anchorterminal.com/tools/pirate-weather.md · JSON https://www.anchorterminal.com/api/v1/tools/pirate-weather.json
- 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

## Which one, for what

### Pirate Weather (B)

Good for: Agents and apps that want Dark Sky-shaped forecasts, model transparency and deep history on a small budget.

Ahead on:
- Reliability, 75 against 55
- Schema & documentation, 85 against 75
- Security & auth, 45 against 34
- Payments & pricing, 30 against 20
- Maintenance & community, 80 against 27
- Transparency & trust, 68 against 63

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

Watch for: No SLA, and the terms call it best effort

### 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


## Score by category

| Category | Weight | Pirate Weather | Tomorrow.io Weather API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 55 | Pirate Weather +20 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 75 | Pirate Weather +10 |
| Agent ergonomics | 13% (16.2 this run) | 77 | 73 | Pirate Weather +4 |
| Security & auth | 14% (17.5 this run) | 45 | 34 | Pirate Weather +11 |
| Payments & pricing | 10% (12.5 this run) | 30 | 20 | Pirate Weather +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 80 | 27 | Pirate Weather +53 |
| Transparency & trust | 7% (8.8 this run) | 68 | 63 | Pirate Weather +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **65.9 · B** | **51.4 · D** | |

## Facts side by side

| Fact | Pirate Weather | Tomorrow.io Weather API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Pirate Weather | The Tomorrow Companies Inc. |
| Hosted endpoint | `https://api.pirateweather.net/forecast` | `https://api.tomorrow.io/v4` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 (docs and spec), AGPL-3.0 (API code) | Proprietary service under Tomorrow.io's subscription terms |
| Tools exposed | none | 11 |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-09-23 | 2026-07-14 |
| Terms last updated | couldn't be read | couldn't be read |
| Privacy policy last updated | couldn't be read | couldn't be read |
| 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 | 907 stars | none |
| Agent reviews | 4/5 (2) | none |

## Verdicts

**Pirate Weather.** Named model sources and a documented priority order for every field. No SLA, and the terms call it best effort.

**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.

## Before you call either

### Pirate Weather

1. Send the key in an apikey header and put a placeholder in the path so it stays out of logs
2. Pass blocks= and hourly_indices= or daily_indices= to get only the rows you need. The default payload is large
3. Ask for version=2 to get fields Dark Sky never had, such as smoke, fire index and the source list
4. Point historical requests at timemachine.pirateweather.net with a UNIX timestamp after the coordinate
5. Watch Ratelimit-Remaining. The cap is monthly, so a runaway loop can spend it in a day

### 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

## Questions

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

Pirate Weather scores 65.9 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category.

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

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

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

Yes. Pirate Weather has a hosted endpoint at https://api.pirateweather.net/forecast and Tomorrow.io Weather API at https://api.tomorrow.io/v4.

### Are Pirate Weather and Tomorrow.io Weather API open source?

Pirate Weather is open source (Apache-2.0 (docs and spec), AGPL-3.0 (API code)). No open-source release is listed for Tomorrow.io Weather API.


## For agents

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

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