Western Australian wine refers to wine produced in Australia's largest state, Western Australia. Although the state extends across the western third of the continent, its wine regions are almost entirely situated in the cooler climate of its south-western tip. Western Australia produces less than 5% of the country's wine output, but in quality terms it is very much near the top.:765
The Swan Valley established in 1829 by Thomas Waters is the historical centre for wine production in Western Australia. However, the state's cooler climate south-western wine regions such as Margaret River, and The Great Southern are considered to be more significant due to the Swan Valley being noted as one of the hottest viticultural regions in the world. Partly because of this, and as a reaction to the emergence of the Margaret River and Great Southern regions spanning the far south western corner of the state a large number of producers have deserted the area with the numbers of vineyards shrinking. In the year 1970, 90 percent of the state's wine was made from grapes grown in the Swan Valley; by 1980 the figure was 59 percent; by 1996 it was 15 percent and still falling.
In the late 1960s, winemaking grew in the southern regions of Western Australia with the influence of Antarctic currents and onshore westerlies offering a more temperate climate for grape production. Despite having only around 7 percent of Australia’s vineyards and a mere 3 percent of grapes crushed, the winemaking regions of the South-West of the state attract a large amount of media attention.
The Great Southern is Australia's largest wine region a rectangle 200 kilometres from east to west and over 100 kilometres from north to south. It has five nominated subregions for wine, namely the Porongurups, Mount Barker, Albany, Denmark, and Frankland River under the Geographical indications legislation as determined by the Australian Wine and Brandy Corporation. The vineyards spread throughout the area have significant variations of terroir and climate dictated in part by the distance however the region is the coolest of Western Australia’s viticultural areas; with a similar maritime influenced Mediterranean climate to Margaret River although with slightly less rainfall. This diverse region is known for Riesling, Chardonnay, Cabernet Sauvignon, Pinot noir, Shiraz, and Malbec.
The Margaret River wine region to the south of Western Australia, receives its temperate climate from the cooling influence of the Indian Ocean. Predominant grape varieties cultivated include Cabernet Sauvignon, Merlot, Sémillion, Sauvignon blanc, Chenin blanc and Chardonnay.
The Swan District, of which the Swan Valley forms part, is the hottest wine region in Australia, with the grape harvest usually beginning in January. The Swan Valley is among the largest sources of Western Australia's wine, with grape varieties such as Verdelho, Chenin blanc, and Chardonnay.