 Due to the offshore Leeuwin Current, the area numbers in the top six regions for marine biodiversity, containing the most southerly coral reefs in the world.Average annual rainfall varies from at the edge of the Wheatbelt region to in the wettest areas near Northcliffe, the Southwestern most tip of Australia, but in the months of November to March, although rain still falls, evaporation exceeds rainfall and it is generally very dry.Plants must be adapted to this as well as the extreme poverty of all soils.