Study finds climate change quintupled likelihood of Australia’s January heatwave

The intense heatwave that swept south-eastern Australia in the second week of January 2026 was made significantly hotter and five times more likely by human-driven climate change.

According to a new analysis by the World Weather Attribution (WWA) group released on January 22. The heatwave occurred despite weak La Niña conditions in the equatorial Pacific, which typically bring cooler weather to Australia. Researchers found that climate change added around 1.6°C to the event, pushing temperatures into dangerous territory and sharply increasing the risk of bushfires and heat-related health emergencies.

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

Hospitals came under significant strain, with one Melbourne facility reporting a 25 per cent surge in emergency admissions. Elderly people, outdoor workers, residents of poorly cooled housing, and those with pre-existing illnesses were among the worst affected. Clinicians in regional South Australia also reported a rise in mental health cases linked to prolonged extreme heat.

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

Despite the severity of the event, the report highlighted one positive development: solar power supplied about 60 per cent of peak electricity demand, with rooftop solar accounting for nearly two-thirds of that contribution.

“The impact of climate change far outweighed natural climate variability,” said Ben Clarke of Imperial College London. “The added heat turned a difficult week into a dangerous one.”

Scientists warned that as extreme heat shifts from a rare occurrence to a regular threat, Australia’s capacity to adapt — particularly for vulnerable communities — is being pushed to its limits.