This Hoya is very common locally in North-western Australia, it usually grows in (geologically) sandstone country between rocks and in crevices. The climate is hot and humid with frequent heavy rains during the wet season (summer). During the dry season (winter) it's hot and dry. It usually has little competition from other plants but on the fairly bare rocky terrain it gets a lot of sun exposure and heat retained by the rocks through the night.

In the photo below it's the vine hanging down the rock face.

During the dry season it's common for it to show extreme desiccation, but with the first rains it picks up quite quickly and returns to "normal".

The flowers are fairly typical of the australis species, previously it used to be H. australis ssp rupicola.