Australia's next summer is not guaranteed to be the hottest on record, but forecasters say it is looking increasingly likely, following a warm start to winter that has already broken temperature records across the country. Many parts of Australia have experienced record early winter maximum and minimum temperatures, with Sydney and Melbourne recording their warmest-ever starts to winter. Daily observations show both cities experienced above-average June temperatures almost every day of the month. Adelaide also recorded above-average June temperatures in its first three weeks, while Hobart and Canberra had mild starts to winter with temperatures well above normal. Perth is the only southern capital with typical June temperatures so far.
Global Context: Unseasonable Heat Worldwide
The unseasonably high temperatures in Australia are part of a global trend driven by global heating, including the early summer heatwave in western Europe and parts of Asia. On 26 June, the UK recorded its hottest-ever June day, with temperatures reaching 37.3°C, surpassing the previous record of 36.1°C in 1976. Much of France, Spain, Italy and Germany reached or exceeded 40°C, with high humidity levels. According to the United Nations, hot and cold extremes are expected in nearly all inhabited regions with increasing global warming.
Winter Outlook: Continued Warmth and Dry Spells
According to the Bureau of Meteorology's seasonal outlooks, abnormally warm conditions are likely to continue for at least the coming weeks, with long periods of dry weather expected, especially in late winter and spring, following the recent El Niño development. However, infrequent cold polar outbreaks can still impact southern Australia due to jet stream 'waviness' south of Australia, which can affect the movement of cold air and low pressure systems. The 2026 Australian ski season has started poorly, but one or two unexpected heavy snowstorms could produce a major turnaround.
Climate Drivers and Atmospheric Changes
Research published earlier this year by Milton Speer and Lance M Leslie of the University of Technology Sydney confirms that 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. The southern hemisphere jet streams and associated storm paths have shifted poleward, meaning once-reliable winter and spring rain-producing systems now often pass south of Australia. Consequently, southern Australia experiences more high pressure systems, resulting in cloudless skies and higher daytime temperatures. Additionally, Pacific Ocean temperatures off the Australian subtropical east coast are well above average, directing warm, humid air over south-east Australia and keeping daily minimum temperatures warmer than average.
Summer Outlook: Hotter and Drier Conditions Likely
Forecasters are warning south-east Australia to expect hotter, drier conditions in this El Niño year, a combination that suggests record heatwaves, droughts and extreme bushfire danger are likely. Melbourne is particularly vulnerable to dry weather because of low dam levels; its catchment level is at 64% and falling, the lowest since the Tinderbox drought of 2017–19. 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 will not break records, as El Niño does not always generate extreme temperatures and fire weather. The southern annular mode might bring more cold fronts, potentially delaying extreme heat. But as things are shaping up, a record-breaking summer looks likely.
