Hmm, I'm still not seeing it…which platform are you testing this on? I would love to have this information, and it sounds like I can probably use Mirror to extract it, but it doesn't seem to be present for me…

Ok so that helped me get it to work. You can get the airQuality number with Mirror(reflecting: weather).descendant("airQuality", "some", "index"). But my guess is that this only works because the playgrounds runner for macOS runs inside a platform binary and WeatherKit checks for this and only populates it in that case. Maybe something they will expose in the future? It's clear that they dogfooded this API for Weather and are using it internally but perhaps it's not quite ready for us yet.

Filed FB10384879: Please expose WeatherKit airQuality data as API