Aemet vs US Weather

AEMET OpenData is the official REST API of Spain's national meteorological agency, publishing forecasts, observations, climatology, and warnings ("avisos") restricted to Spanish territory. Requests return a metadata JSON envelope containing a signed URL that must be fetched separately to retrieve the actual payload (JSON, XML, or CSV depending on endpoint), and the service is documented via an interactive Swagger UI and machine-readable OpenAPI spec.

The National Weather Service API serves official US government forecasts, active alerts, and observation-station data as GeoJSON and JSON-LD feeds, with no signup or API key required. It's widely used by third-party weather apps and accepts direct browser calls, though it requires a descriptive User-Agent header identifying your application on every request.