Hong Kong Observatory vs IPMA

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.

IPMA's open-data service is a plain directory of continuously-refreshed static JSON files, not just a single forecast endpoint: it covers daily/hourly weather forecasts, real-time station observations, sea-area and district warnings for mainland Portugal, the Azores and Madeira, plus separate seismic and biology (pollen) datasets from the same institute. No registration is required, though IPMA asks heavy users to email its webmaster for usage statistics.