IPMA vs openSenseMap

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.

openSenseMap is the open, non-profit citizen-science platform behind the University of Munster's senseBox project, serving live and historical readings from thousands of crowdsourced environmental sensor stations worldwide, covering not just temperature/humidity but also particulate matter, noise and other phenomena. Reading data is fully open and keyless (accounts are only needed to register or post data from your own senseBox), and the full historical archive is separately mirrored on an archive subdomain.