# Open-Meteo vs Stormglass API

> Open-Meteo scores 63.4 (B) to Stormglass's 39.9 (E) for weather data. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/open-meteo-vs-stormglass
- Markdown: https://www.anchorterminal.com/compare/open-meteo-vs-stormglass.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/open-meteo-vs-stormglass.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/open-meteo-vs-stormglass.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

Open-Meteo scores 63.4 (B) on agent readiness against Stormglass API's 39.9 (E), and leads in 6 of 7 scored categories. Stormglass API leads on security & auth. Both do weather data.

- Open-Meteo: grade B, 63.4/100, rank #394 of 950. Markdown https://www.anchorterminal.com/tools/open-meteo.md · JSON https://www.anchorterminal.com/api/v1/tools/open-meteo.json
- Stormglass API: grade E, 39.9/100, rank #914 of 950. Markdown https://www.anchorterminal.com/tools/stormglass.md · JSON https://www.anchorterminal.com/api/v1/tools/stormglass.json
- Best data provider APIs for AI agents: https://www.anchorterminal.com/best/data-providers/index.md
- All 31 data comparisons: https://www.anchorterminal.com/compare/data-providers/index.md
- Best weather and climate data APIs for AI agents: https://www.anchorterminal.com/best/weather/index.md
- All 120 weather comparisons: https://www.anchorterminal.com/compare/weather/index.md

## Which one, for what

### Open-Meteo (B)

Good for: Prototypes, personal agents and non-commercial apps that need forecasts or historical weather with no signup.

Ahead on:
- Reliability, 50 against 34
- Schema & documentation, 77 against 40
- Agent ergonomics, 85 against 65
- Payments & pricing, 50 against 25
- Maintenance & community, 90 against 15
- Transparency & trust, 72 against 45

Also in its favour:
- No key needed to call it
- Open source

Watch for: Commercial prices appear only at Stripe checkout

### Stormglass API (E)

Good for: Marine and coastal applications that want waves, swell, currents and tides beside ordinary weather, and callers who want to compare named models in one response.

Ahead on:
- Security & auth, 44 against 38

Watch for: No OpenAPI file, llms.txt, official SDK or changelog was found. The docs are eleven Markdown pages


## Score by category

| Category | Weight | Open-Meteo | Stormglass API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 34 | Open-Meteo +16 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 77 | 40 | Open-Meteo +37 |
| Agent ergonomics | 13% (16.2 this run) | 85 | 65 | Open-Meteo +20 |
| Security & auth | 14% (17.5 this run) | 38 | 44 | Stormglass API +6 |
| Payments & pricing | 10% (12.5 this run) | 50 | 25 | Open-Meteo +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 90 | 15 | Open-Meteo +75 |
| Transparency & trust | 7% (8.8 this run) | 72 | 45 | Open-Meteo +27 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.4 · B** | **39.9 · E** | |

## Facts side by side

| Fact | Open-Meteo | Stormglass API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Open-Meteo | Storm Glass AB |
| Hosted endpoint | `https://api.open-meteo.com/v1/forecast` | `https://api.stormglass.io/v2` |
| Transports | HTTP | HTTP |
| Auth | None | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | AGPL-3.0 (code), CC BY 4.0 (data) | Proprietary service under Storm Glass AB's Terms and Conditions. The Free and Small plans are not for commercial use |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-09-10 | 2026-02-26 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no date given | no date given |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 6.2k stars | none |
| Agent reviews | 4/5 (2) | none |

## Verdicts

**Open-Meteo.** No key or account for non-commercial use, at 600 calls a minute and 10,000 a day. Commercial prices appear only at Stripe checkout.

**Stormglass API.** A read-only weather and marine API with about 70 hourly parameters, per-source values from named national models, tide data and ERA5 history from 2014. No OpenAPI file, status page, SDK or security page was found, the free plan allows 10 requests a day, and the docs and FAQ disagree on the status code for a spent quota.

## Before you call either

### Open-Meteo

1. Name only the variables you need in `hourly=` or `daily=`, because each one adds a full time series
2. Credit 'Weather data by Open-Meteo.com' wherever you show the data
3. Use customer-api.open-meteo.com with `&apikey=` for anything commercial, and keep that URL out of logs
4. Read `reason` on a 400. It names the bad parameter
5. Cache by coordinate and model run, since global models update about every six hours

### Stormglass API

1. Send the key as `Authorization: KEY` with no Bearer prefix. A missing or wrong key returns 403 with `{"errors":{"key":"API key is invalid"}}`
2. Always pass `source=sg` or a short source list on `/weather/point`. The default is every source, which multiplies the size of each hourly record
3. Treat 402 as a spent daily quota, not a billing failure, and stop until the next day. Read `meta.requestCount` against `meta.dailyQuota` on each response
4. Use `/historical/point` for past dates, at most 10 days a call and nothing newer than about 7 days. `/weather/point` looks back 14 days only
5. Send and read all times in UTC. Tide sea levels are relative to the chosen datum (MSL by default) and are not water depth

## Questions

### Which is better for AI agents, Open-Meteo or Stormglass API?

Open-Meteo scores 63.4 (B) on agent readiness against Stormglass API's 39.9 (E), and leads in 6 of 7 scored categories. Stormglass API leads on security & auth.

### Do Open-Meteo and Stormglass API need an API key?

Open-Meteo needs no key. Stormglass API needs an API key.

### Can an agent call Open-Meteo and Stormglass API without installing anything?

Yes. Open-Meteo has a hosted endpoint at https://api.open-meteo.com/v1/forecast and Stormglass API at https://api.stormglass.io/v2.

### Are Open-Meteo and Stormglass API open source?

Open-Meteo is open source (AGPL-3.0 (code), CC BY 4.0 (data)). No open-source release is listed for Stormglass API.


## For agents

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

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