Australia is experiencing an unusually warm start to winter, with many regions breaking early winter temperature records. Sydney and Melbourne have recorded their warmest ever starts to winter, with daily observations showing above-average June temperatures almost every day. Adelaide also saw above-average June temperatures in its first three weeks, while Hobart and Canberra had mild starts with temperatures well above normal. Only Perth among southern capitals has experienced typical June temperatures so far.
What Lies Ahead for the Rest of Winter?
According to the Bureau of Meteorology's seasonal outlooks, abnormally warm conditions are likely to continue for at least the coming weeks. Long periods of dry weather are expected, especially in late winter and spring, following the recent El Niño development. However, infrequent cold polar outbreaks could still impact southern Australia due to jet stream 'waviness' south of the continent. This waviness refers to the meandering of air currents as they form the jet stream, which can move in a north-south direction instead of west to east, affecting the movement of cold air and low pressure systems.
The 2026 Australian ski season has started poorly, with insufficient snow cover. However, one or two unexpected heavy snowstorms could turn the season around significantly.
Part of a Global Trend
Australia's warm winter is part of a worldwide pattern of unseasonably high temperatures. Europe has experienced an early summer heatwave, with the United Kingdom recording its hottest ever June day on June 26, reaching 37.3°C, surpassing the previous record of 36.1°C set in 1976. Much of France, Spain, Italy, and Germany reached or exceeded 40°C, accompanied by high humidity. This unusually early and intense heatwave confirms that climate extremes are becoming the new normal.
Many nations are facing their warmest winters on record due to accelerated global warming since the 1990s, driven by human-made climate change. The United Nations predicts that hot and cold extremes will increase in nearly all inhabited regions with rising global temperatures.
Scientific Explanations
Research published earlier this year confirms that the unseasonable warmth is due to the warming of Earth's atmosphere and oceans. Global warming causes changes in large-scale southern hemisphere atmospheric circulation patterns and amplifies the impacts of known climate drivers—large-scale processes in the atmosphere and ocean that dictate weather patterns and climate variability.
The southern hemisphere jet streams, fast-flowing narrow bands of wind in the upper atmosphere, and associated storm paths have shifted poleward. Once-reliable winter and spring rain-producing systems now often pass south of Australia, leading to more high pressure systems over southern Australia. This results in cloudless skies and higher daytime temperatures, similar to the current heat dome in western Europe.
Additionally, Pacific Ocean temperatures off the Australian subtropical east coast are well above average. Consequently, Tasman Sea high-pressure systems are directing warm, humid air over southeast Australia, making daily minimum temperatures warmer than average.
Implications for Australia's Summer
Experts warn that Australia's next summer could break heat records. Accelerated global warming continues, and the eastern half of the United States recently issued an early summer heat dome warning. Forecasters are warning southeast Australia to expect hotter, drier conditions in this El Niño year—a frightening combination that suggests record heatwaves, droughts, and extreme bushfire danger are likely.
Melbourne is particularly vulnerable to dry weather due to low dam levels. Its catchment level is at 64% and falling, the lowest since the Tinderbox Drought of 2017–19. Daily observational data shows Melbourne missed the rain that replenished other southern capital cities in autumn and spring. Melbourne and its catchment are in the rain shadow of the Great Dividing Range, which dries out warm, humid subtropical air.
However, there is still a possibility that Australia's summer may not break records. El Niño does not always generate extreme temperatures, dry conditions, and fire weather. The Southern Annular Mode, a climate driver that can influence rainfall and temperature in Australia, might bring more cold fronts. Therefore, extreme heat might not occur in late spring or early summer. But given current trends, it appears increasingly likely.
