Climate change drove Australia’s January heatwave, making it five times more likely: Study

The severe heatwave that gripped south-eastern Australia in early January 2026 was made significantly hotter and five times more likely by human-induced climate change, a new analysis by the World Weather Attribution (WWA) group has found.

Released on January 22, the study said climate change intensified the heatwave by about 1.6°C, pushing temperatures to dangerous levels and greatly increasing the risks of bushfires and heat-related health emergencies. The extreme heat unfolded despite weak La Niña conditions in the equatorial Pacific, which usually bring cooler weather to Australia. Researchers said this underscored the dominant role of global warming over natural climate variability.

Between January 5 and 10, maximum temperatures crossed 40°C in several major cities, including Melbourne and Sydney. Melbourne recorded a peak of 44.4°C on January 9, as hot and dry conditions combined with strong winds to create fire-prone weather comparable to the deadly 2009 Black Saturday bushfires.

Health services were stretched, with one Melbourne hospital reporting a 25 per cent increase in emergency admissions. The elderly, outdoor workers, people living in poorly cooled homes and those with pre-existing health conditions were among the worst affected. Doctors in regional South Australia also reported a rise in mental health cases linked to prolonged exposure to extreme heat.

According to WWA scientists, in today’s climate — about 1.3°C warmer than the pre-industrial era — such a heatwave can be expected roughly once every five years. Without global warming, it would likely occur only once every 25 years. If global temperatures rise to around 2.6°C, similar events could strike every two years.

The report noted one mitigating factor: solar energy met about 60 per cent of peak electricity demand during the heatwave, with rooftop systems contributing nearly two-thirds of that share. “The influence of climate change far outweighed natural climate variability,” said Ben Clarke of Imperial College London. “The additional heat transformed a challenging period into a dangerous one.”

Scientists warned that as extreme heat becomes more frequent, Australia’s ability to adapt — especially for vulnerable communities — is being increasingly tested.