Australia heads into southern hemisphere winter after an unusually warm and dry April. Temperatures soared above average across most regions, with New South Wales recording its second-driest April on record. In Victoria’s Gippsland, Bairnsdale saw just 5.4mm of rain—the lowest since 1943.
High Pressure Systems Drive the Dry Spell
April’s dryness contrasted sharply with the heavy rains of February and March. A stalled tropical low-pressure system then drenched central Australia, filling Kati Thanda-Lake Eyre and greening the deserts. Vegetation surged rapidly in these areas.
Persistent high-pressure systems dominated eastern Australia in April. Descending air within these systems prevents cloud formation, delivering clear, sunny days without rain. Cloudless nights allow daytime heat to escape into space, resulting in cooler mornings and occasional fog over the east.
These high-pressure ridges blocked cold fronts from the west, diverting them southward near the Great Australian Bight and bypassing eastern states.
Climate Change Amplifies the Heat
High pressure alone does not explain the warmth. The past 13 autumns feature daily maximum temperatures exceeding the 1961–90 baseline average. Australia’s air temperatures now run 1.51°C hotter than in 1910, driven by greenhouse gas emissions from fossil fuels.
Global warming strengthens the subtropical ridge—a band of high pressure around 30°S latitude, spanning Perth to Sydney. This shift deflects cold fronts, potentially cutting autumn and winter rainfall in southern Australia.
El Niño on the Horizon?
Speculation surrounds a possible strong El Niño this year, though conditions remain neutral for now. Warmer subsurface ocean waters in the central Pacific signal potential development by late winter. El Niño typically weakens trade winds, warming eastern Australia’s winters and springs while reducing rain-bearing systems.
Historical droughts often coincide with El Niño events, but direct links to April’s weather remain unconfirmed without an active event.
Winter Weather Outlook
The subtropical ridge shifts north in winter, allowing more cold fronts to reach southern Australia and boosting rainfall there. An emerging El Niño could temper this pattern.
Long-range forecasts predict above-average winter temperatures nationwide. May rainfall likely falls below normal across most areas, except southern Victoria, southwest Tasmania, and central Western Australia, where levels stay average. Northern Queensland may see above-normal rain.
From June to August, drier conditions threaten the southwest and southeast. Wetter prospects emerge in northern Queensland, northeast Northern Territory, and central Western Australia. Farmers and emergency managers should monitor updates closely, as longer-term predictions carry higher uncertainty.
