# OpenWeather One Call API vs Visual Crossing Weather API

> Visual Crossing Weather API has a score of 60.3 (C) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 21 points. Category scores, facts, verdicts and agent notes side by side.

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- Slim: https://www.anchorterminal.com/compare/openweather-one-call-vs-visual-crossing.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openweather-one-call-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: 2026-10-04

Visual Crossing Weather API has a score of 60.3 (C) against OpenWeather One Call API's 57.4 (C). Both do weather current. The largest gap is reliability, 21 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
- Visual Crossing Weather API: grade C, 60.3/100, rank #251 of 452. Markdown https://www.anchorterminal.com/tools/visual-crossing.md · JSON https://www.anchorterminal.com/api/v1/tools/visual-crossing.json

## Which one, for what

Pick OpenWeather One Call API for payments & pricing (+20).

Pick Visual Crossing Weather API for reliability (+21), schema & documentation (+6), agent ergonomics (+5).

## Score by category

| Category | Weight | OpenWeather One Call API | Visual Crossing Weather API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 45 | 66 | Visual Crossing Weather API +21 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 68 | 74 | Visual Crossing Weather API +6 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 78 | Visual Crossing Weather API +5 |
| Security & auth | 14% (17.5 this run) | 42 | 40 | OpenWeather One Call API +2 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | OpenWeather One Call API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 58 | OpenWeather One Call API +2 |
| Transparency & trust | 7% (8.8 this run) | 62 | 61 | OpenWeather One Call API +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.4 · C** | **60.3 · C** | |

## Facts side by side

| Fact | OpenWeather One Call API | Visual Crossing Weather API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenWeather | Visual Crossing |
| Hosted endpoint | `https://api.openweathermap.org/data/3.0/onecall` | `https://weather.visualcrossing.com/VisualCrossingWebServices/rest/services/timeline` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | none |
| Tools exposed | 6 | 1 |
| 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 | yes |
| MCP registry | `org.openweathermap/agents` | not listed |
| Last release | none | none |
| Popularity | none | none |
| 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.

**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

### 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

### 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

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