Climate of South Australia

The climate of South Australia varies, from hot and dry in the interior to the milder, wetter climates of the southern Mount Lofty Ranges and the southeast coast of South Australia. Median annual rainfall ranges from about 100 mm in the area east of Lake Eyre to more than 1000 mm on the higher parts of the Mount Lofty Ranges.

Physical features

The State of South Australia occupies approximately the central third of the southern half of the continent of Australia with the ocean to the south. From the head of the Great Australian Bight, near the State's western border, the coastline tends southeastwards to the Victorian border. This trend is interrupted by two major indentations, Spencer Gulf and Gulf St Vincent. The waters of these two gulfs have a moderating influence on temperatures along their coasts. Kangaroo Island, to the west of Victor Harbor, is the predominant island off the South Australian coast. . Large parts of South Australia are relatively flat or slightly undulating and approximately half the State is less than 150 metres above sea level. The most significant mountain ranges are the Flinders and the Mount Lofty Ranges that extend from Cape Jervis in the south to the northern end of Lake Torrens. North of Peterborough there is a divergence from the main range that stretches via the Glary Ridges to the Barrier Range and Broken Hill in New South Wales. These ranges influence the climate by enhancing the rainfall in their immediate vicinity. Temperature also decreases with increasing altitude. The western half of the State is largely occupied by a low plateau, over which an intermittent series of low ranges stretches from the Flinders to the somewhat higher Musgrave Ranges in the far northwest.

Climate controls

The seasonal variation of weather in South Australia is controlled by the position of the subtropical ridge of high pressure: During the warmer half of the year (November to April), this ridge is located along latitudes to the south of the Australian continent. High pressure systems (anticyclones) generally move eastwards along the ridge but have a favoured position south of the Great Australian Bight. Consequently, the most frequent air stream across most of South Australia during this period is from the southeast to east. Although cold fronts associated with southern low pressure systems penetrate the ridge from time to time during summer, they generally fail to produce much useful rain.

Warm moist air of tropical origin occasionally moves into the State from the north during summer and thunderstorms may then develop.

In autumn the subtropical ridge moves north and remains over the Australian continent for most of the colder half of the year (May to October). During this period favoured locations for centres of anticyclones are the Great Victoria Desert and central New South Wales. The most frequent winds are from the northwest to southwest. Frontal systems associated with depressions traveling eastwards across the ocean have a significant influence on the weather in southern South Australia during this season.