Wei-Assipu-tepui has a maximum elevation of around . Its summit plateau is highly dissected and generally inclined south-southwest (towards the Brazilian side). The rocky summit is partially forested, with flowering plants of the genus Bonnetia featuring prominently. It also hosts a number of carnivorous plants, including Heliamphora glabra, Heliamphora nutans, and the natural hybrid between the two. The various rock cavities of Wei-Assipu-tepui are home to nesting colonies of white-collared swifts (Streptoprocne zonaris) and oilbirds (Steatornis caripensis). For the latter species, Wei-Assipu-tepui is the easternmost recorded locality in mainland South America, and the first known nesting site in Brazil. The mountain's summit supports a greater variety of herpetofauna than the less vegetated plateaus of nearby Roraima-tepui, Kukenán-tepui, Yuruaní-tepui, and Ilú-tepui. Day temperatures of 17 °C have been recorded on the summit plateau, falling to 12 °C overnight, with slightly lower values in the more sheltered caves.