Meteomatics Weather API vs OpenWeather One Call API

Meteomatics Weather API

A public OpenAPI file, a hosted MCP server whose nine tools are all marked read-only, a published SLA with compensation and ISO 27001 certification suit company use. Access needs a sales contract, with no public price, free tier or self-serve signup found, no status page, and REST calls that authenticate with a username and password.

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.

Meteomatics Weather API

1. Ask the account owner for credentials first. There is no signup, and both the REST API and the MCP server need a Meteomatics account with API access
2. Build REST URLs as validdatetime/parameters/location/format, for example 2026-10-08T00:00:00Z/t_2m:C/52.52,13.40/json. Parameter names carry their unit after a colon
3. Keep each query to 10 locations and 10 parameters unless the contract says otherwise, and use POST when a GET URL passes 2,000 characters
4. Send credentials or the token in the Authorization header. Avoid the documented access_token query parameter, which puts the token in URLs and logs
5. Read /user_stats_json before a large job. It reports queries sent and the contract's limits, and 429 means a limit is spent
6. Treat reserved values such as -888 and -999 as invalid or missing data, and shrink the request when a 408 arrives after the 300-second timeout

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