Leaving the maps, and speaking generally, I would point out that in both the Northern and Southern Hemispheres is a belt or zone of high pressure, separating the tropical and polar zones of low pressure at the latitude where the return trade and polar winds descend towards the surface of the earth.

The southern belt passes over the extra-tropical or temperate parts of Australia. It is made up of long loops, or anticyclonic areas, being broken up at intervals by low pressure intrusions from the tropics and northerly extensions of V-shaped depressions from the south. When these join they form a barometric trough or valley, effecting a complete rupture of the anticyclonic belt. The position or latitude of this anticyclonic belt depends on the time of the year, and varies in different years. Normally, during the winter the crest of the "high" lies over the interior. approximately about latitude 29° or 30° (vide map 6). North of this the continent is swept by the dry south-east trade winds, whilst to the south we have, in South Australia, a prevalence of dry northerly (north-east to north-west) winds, varied by strong west and southwest winds as coastal depressions pass from west to east, with rain and squally weather. On the east coast west winds prevail during the winter.

The character of our winter season, in South Australia especially, depends very closely on the position of this wall, as it were, of high barometers, which plays a very important part in Australian climate. If it lies too far south, or near the coast, the winter over the southern districts of the colony (I am speaking of South Australia) is dry, but we may, and occasionally do, have under these conditions good rains in the north, due to the extension of tropical depressions bringing rain over the interior of Queensland, New South Wales, and South Australia east of Lake Eyre and the Flinders Range.

On the other hand, if the anticyclonic areas keep more to the north, the southern or coastal V depressions extend further inland, at times being felt as far as the tropics, and we have copious rains all over the colony, as well as in Victoria and western New South Wales. As the depressions pass the winds veer from north-east and north to north-west, west, and south-west. Steady rains set in with the wind at north-east to north, heaviest at north-west, and break up with heavy showers and squalls at south-west, sometimes accompanied by heavy thunderstorms, while the wind is north-west to south-west.

Bureau of Meteorology