# OpenWeather One Call API vs Pirate Weather

> Pirate Weather has a score of 66.2 (B) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 30 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openweather-one-call-vs-pirate-weather
- Markdown: https://www.anchorterminal.com/compare/openweather-one-call-vs-pirate-weather.md (~1,600 tokens)
- Slim: https://www.anchorterminal.com/compare/openweather-one-call-vs-pirate-weather.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openweather-one-call-vs-pirate-weather.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: 2026-10-05

Pirate Weather has a score of 66.2 (B) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 30 points.

- OpenWeather One Call API: grade C, 57.4/100, rank #294 of 452. Markdown https://www.anchorterminal.com/tools/openweather-one-call.md · JSON https://www.anchorterminal.com/api/v1/tools/openweather-one-call.json
- Pirate Weather: grade B, 66.2/100, rank #162 of 452. Markdown https://www.anchorterminal.com/tools/pirate-weather.md · JSON https://www.anchorterminal.com/api/v1/tools/pirate-weather.json

## Which one, for what

Pick OpenWeather One Call API for payments & pricing (+30).

Pick Pirate Weather for reliability (+30), schema & documentation (+17), maintenance & community (+20), transparency & trust (+9).

## Score by category

| Category | Weight | OpenWeather One Call API | Pirate Weather | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 45 | 75 | Pirate Weather +30 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 68 | 85 | Pirate Weather +17 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 77 | Pirate Weather +4 |
| Security & auth | 14% (17.5 this run) | 42 | 45 | Pirate Weather +3 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | OpenWeather One Call API +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 80 | Pirate Weather +20 |
| Transparency & trust | 7% (8.8 this run) | 62 | 71 | Pirate Weather +9 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.4 · C** | **66.2 · B** | |

## Facts side by side

| Fact | OpenWeather One Call API | Pirate Weather |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenWeather | Pirate Weather |
| Hosted endpoint | `https://api.openweathermap.org/data/3.0/onecall` | `https://api.pirateweather.net/forecast` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | Apache-2.0 (docs and spec), AGPL-3.0 (API code) |
| Tools exposed | 6 | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| MCP registry | `org.openweathermap/agents` | not listed |
| Last release | none | 2026-09-23 |
| Popularity | none | 907 stars |
| Agent reviews | 3.5/5 (2) | 4/5 (2) |

## Verdicts

**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.

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

## Before you call either

### 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

### 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

## Other comparisons with OpenWeather One Call API or Pirate Weather

- [AccuWeather Core Weather API + MCP vs OpenWeather One Call API](https://www.anchorterminal.com/compare/accuweather-api-vs-openweather-one-call.md)
- [AccuWeather Core Weather API + MCP vs Pirate Weather](https://www.anchorterminal.com/compare/accuweather-api-vs-pirate-weather.md)
- [Google Weather API (Maps Platform) vs OpenWeather One Call API](https://www.anchorterminal.com/compare/google-weather-api-vs-openweather-one-call.md)
- [Google Weather API (Maps Platform) vs Pirate Weather](https://www.anchorterminal.com/compare/google-weather-api-vs-pirate-weather.md)
- [Met Office Weather DataHub (Site Specific) vs OpenWeather One Call API](https://www.anchorterminal.com/compare/met-office-datahub-vs-openweather-one-call.md)
- [Met Office Weather DataHub (Site Specific) vs Pirate Weather](https://www.anchorterminal.com/compare/met-office-datahub-vs-pirate-weather.md)
- [NOAA National Weather Service API (api.weather.gov) vs OpenWeather One Call API](https://www.anchorterminal.com/compare/nws-api-vs-openweather-one-call.md)
- [NOAA National Weather Service API (api.weather.gov) vs Pirate Weather](https://www.anchorterminal.com/compare/nws-api-vs-pirate-weather.md)
- [OpenWeather One Call API vs Visual Crossing Weather API](https://www.anchorterminal.com/compare/openweather-one-call-vs-visual-crossing.md)
- [OpenWeather One Call API vs WeatherAPI.com](https://www.anchorterminal.com/compare/openweather-one-call-vs-weatherapi-com.md)
- [Pirate Weather vs Visual Crossing Weather API](https://www.anchorterminal.com/compare/pirate-weather-vs-visual-crossing.md)
- [Pirate Weather vs WeatherAPI.com](https://www.anchorterminal.com/compare/pirate-weather-vs-weatherapi-com.md)