Essentially, the soils derive from granitic and gneissic rock over which laterite has formed. The region can be divided in three sub-regions: the cooler south between Witchcliffe and Karridale with predominantly lateritic gravelly loamy sands and sandy loams; the warm and sunnier Margaret River in the centre with predominantly gravelly loams, but some gritty sandy loams and granitic gravels; and Wilyabrup in the north with similar soils, but slightly cooler temperatures. This is entirely consistent with style, the wines from Willyabrup being more generous than the highly structured wines of the north and the elegant styles of the south. The region is also subject to southeast trade winds.
The climate is strongly maritime influenced, more so than any other major Australian region. It has the lowest mean annual range of only 7.6C, and for good measure has the most marked Mediterranean climate in terms of rainfall, with only 200mm of the annual 1160mm falling between October and April. The low diurnal and seasonal temperature range means an unusually even accumulation of warmth, while spring frosts are very rare and highly localised. Overall the climate is similar (in terms of warmth) to that of Pomerol and St Emilion in a dry vintage, hence the quality of its Cabernet Sauvignon, Merlot and so forth.
The landscape constantly varies, given character by the abundance of small creeks and gentle valleys as well as the profusion of native trees, shrubs and flowers. The principal soil type is that of the ridge which runs from Cape Naturaliste to Cape Leeuwin. It is predominantly gravelly or gritty sandy loam formed directly from the underlying granite and gneissic rock.