Aemet vs Hong Kong Observatory

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 Hong Kong Observatory's Open Data API exposes roughly 50 machine-readable datasets covering real-time weather observations, 9-day forecasts, lightning counts, tropical cyclone tracking, tidal predictions, UV index and radiation levels, plus historical rainfall and sunshine records, for Hong Kong and nearby waters. It is a free, keyless service built for machine-to-machine consumption, mirrored on the government's data.gov.hk portal alongside the Observatory's own documented endpoint.