Unlike much of the Northern Hemisphere, which follows a predictable four-season cycle, Australia is a continent defined by hydrological extremes. It does not have a single "rainy season." Instead, it operates on a split system: a monsoonal north and a temperate south, bridging a vast arid interior. The timing of rainfall is dictated by the collision of the tropics and the westerlies, often modulated by one of the most powerful climate drivers on Earth.
Australia’s rainfall seasonality is uniquely complex due to its large latitudinal range and influence from multiple climate drivers. Unlike temperate regions with a single wet season, Australia exhibits distinct rainfall regimes: a monsoon season in the north, a winter-dominant system in the southwest and southeast, and an arid/asymmetric pattern in the interior. This paper reviews the climatological mechanisms (monsoon, subtropical ridges, cut-off lows, ENSO, IOD, SAM), regional seasonal timing, and the implications for agriculture, water resources, fire regimes, and flooding. australia rain season