is it also possible to add a temperature/humidity sensor
sure, but it depends on the brand / used protocol
the easiest thing is to power the device and see what debug output you will get.
should look something like that :
after that you will have to create a device looking something like that
"name": "Temperatur Balkon",
and at the gui it’s looking like that
here you can see what protocols / brands are supported.
if your weather device is not supported we can try to implement it.
hm … now i read your post again - do you mean a dht device or an bmp180, ds18b20 or similar?
also possible. but that’s another story …