Met.no
Devices & Services > Met.no adds a location by latitude/longitude - no API key needed. The
Norwegian Meteorological Institute's own locationforecast API is free and
unauthenticated, just a descriptive User-Agent header Athena already sends automatically.
What you get
The same shape every weather integration in Athena uses: current conditions (temperature, humidity, pressure, wind, cloud cover, precipitation, condition) plus a 5-day forecast (daily min/max temperature and condition), all read-only sensors working with Dashboard cards, History, and Automations exactly like every other integration.
Polling
Polls every 30 minutes, matching Met.no's own published guidance to poll infrequently rather than hammering a free, unauthenticated API.
One of four weather integrations Athena supports (alongside OpenWeatherMap, AccuWeather, and Finnish Meteorological Institute) - the only one needing no API key at all, so it's the fastest to set up if you don't already have a key for one of the others.