Southeastern Australia hit by near-50°C heatwave as fires, blackouts and water failures expose system strain

On the night a bushfire crept toward Gellibrand in Victoria’s Otway Ranges, residents’ phones blared with a blunt warning: it was too late to leave.

Power had already failed in the 40-degree heat. By morning, flames had destroyed the town’s water treatment plant, cutting safe drinking water just as a searing heatwave pushed temperatures across inland South Australia, Victoria, New South Wales and southern Queensland toward 50 degrees Celsius.

From Ceduna’s 49.5-degree Australia Day high on the South Australian coast to record-breaking heat in Victoria’s Mallee and smoke haze drifting over Sydney, the late-January heatwave has not only toppled temperature records. It has also laid bare how quickly essential systems — electricity, water, health services and fire response — can falter in a climate that is already about 1.5 degrees warmer than a century ago.

Meteorologists describe the event as the most significant heatwave to hit southeastern Australia since the 2019–20 Black Summer, with some inland towns enduring more than a week of temperatures above 40 degrees.

Heat records fall across four states

The heatwave built over central and southeastern Australia from about Jan. 24 as a strong, stagnant high-pressure system — sometimes called a heat dome — settled over the continent’s interior. Clear skies, light winds and an already hot late-January sun allowed heat to build day after day.

On Australia Day, Jan. 26, the South Australian town of Ceduna on the Great Australian Bight reached 49.5 C, its hottest day on record and among the highest temperatures ever observed on Australia’s southern coastline. That night, Adelaide recorded a minimum of 34.1 C, its warmest overnight temperature on record.

The next day brought a historic peak in Victoria and parts of inland New South Wales and South Australia. In Victoria’s northwest, Walpeup and Hopetoun each reached 48.9 C, setting a new all-time state record and edging past the 48.8 C mark measured at Hopetoun on Black Saturday in 2009.

Mildura, on the Murray River, climbed to 48.6 C, its hottest day since records began. Warrnambool on Victoria’s southwest coast hit 45 C, also a record. Melbourne’s Olympic Park station reached 43 C, while some western suburbs exceeded 45 C.

Across the border, Renmark in South Australia peaked at 49.6 C, its highest on record and among the state’s hottest readings ever. Fowlers Gap in far western New South Wales reached 49.1 C, a site record and one of the highest temperatures recorded in that state. On Jan. 28, Borrona Downs in northwestern New South Wales was reported near 49.2 C, as the hottest air shifted north and east over inland New South Wales and southwest Queensland.

In the alpine regions, usually a refuge from summer heat, Falls Creek and Perisher Valley recorded maximums above 30 C for the first time.

The Bureau of Meteorology issued severe and extreme heatwave warnings over successive days for large parts of South Australia, Victoria, New South Wales, southern Queensland and the Australian Capital Territory. In a severe weather update, the bureau said “an unrelenting heatwave continues across much of central and south-east Australia,” warning that inland areas could expect “mid to high 40s all the way into the weekend.”

Health systems brace for the deadliest hazard

While bushfires often dominate public attention, health authorities stressed that heat itself is Australia’s deadliest natural hazard.

“Victoria is experiencing a rare heatwave event,” the state’s chief health officer, Dr. Caroline McElnay, warned in an advisory issued Jan. 26. “Heat-related illness kills more Australians than any other natural disaster.”

The advisory urged residents to stay hydrated, avoid outdoor activity in the hottest parts of the day, use air conditioning or fans if possible and check on older people, young children and those with chronic illnesses. It also recommended preparing for potential power failures during the hottest days.

National data reinforce the concern. The Australian Institute of Health and Welfare has reported that extreme heat was responsible for 7,104 injury hospitalizations and 293 deaths between 2012 and 2022, more than for any other type of extreme weather, including bushfires and floods.

During this heatwave, ambulance services and emergency departments in several states reported spikes in call-outs for heat stress, dehydration and cardiac events. In some cases, those calls coincided with power outages that left people without cooling.

Power grid holds — until the poles and wires fail

The heat sent electricity demand soaring as air conditioners ran flat out across the National Electricity Market, which supplies power to eastern and southern Australia.

The Australian Energy Market Operator had said in advance that it expected to have sufficient generation to meet demand. Early indications from the event support that view: the main problems emerged not in overall supply, but in the distribution networks that deliver power to homes and businesses.

Victoria was hardest hit. Over several days from Jan. 26, more than 100,000 customers lost power at some point as extreme heat, bushfires and strong winds combined to damage lines and transformers. At one point, more than 25,000 homes were without electricity simultaneously across Melbourne and regional areas. Some communities near active firegrounds remained without power for days.

Distribution companies cited heat-stressed equipment, fire damage and trees brought down across lines when a gusty cool change arrived after the hottest period. State officials acknowledged that in some cases, aging infrastructure had struggled to cope.

Victorian Energy Minister Lily D’Ambrosio publicly criticized the private companies that operate the state’s poles and wires, saying mass outages showed networks were not resilient enough to heatwaves and fires that are becoming more frequent and severe.

“We will be requiring distribution businesses to develop and publish five-year resilience plans for high-risk areas,” she said, arguing that longer-term planning was needed to ensure lines and substations could withstand compound extreme events.

Opposition leaders countered that the state government had had years to upgrade infrastructure and streamline planning approvals, accusing it of using the companies as a scapegoat.

For residents, the politics offered little solace in houses that remained above 30 C well after dark. In Melbourne’s outer suburbs, families described putting wet towels on children to help them sleep when neither fans nor refrigerators could be used. Some turned to shopping centers, libraries or friends’ homes in suburbs where power remained on.

Fire, smoke and a town without water

In Victoria, the heatwave unfolded on top of an already severe bushfire season. By late January, more than 435,000 hectares had burned across the state, including large fires in the northeast near Walwa, in the high country around Wonnangatta and Dargo, and in the Otways in the state’s southwest.

On Jan. 27, the Country Fire Authority declared a total fire ban for the entire state. Chief Officer Jason Heffernan said the ban was declared “due to ongoing fires in the landscape, combined with the extreme heat,” warning that any new ignition could spread rapidly.

In the Otways, the Carlisle River–Gellibrand fire jumped containment lines and pushed toward small communities nestled in forest. At times, emergency messages told residents it was too late to leave safely and warned that radiant heat from the fire front could be fatal.

The blaze also exposed another layer of vulnerability. The local water treatment plant at Gellibrand was damaged by fire, rendering tap water unsafe. As temperatures remained in the high 30s and low 40s, residents and firefighters depended on trucked bottled water and emergency supplies until repairs could be made.

Elsewhere, smoke from Victorian fires was carried hundreds of kilometers by strong upper-level winds, producing a haze over Sydney despite the absence of major local fires in New South Wales.

Farmers across fire-affected and heat-stricken regions reported heavy losses. Victorian authorities and industry groups said more than 40,000 livestock had died from fire and heat stress, with an estimated value of about 20 million Australian dollars. Producers also warned of ongoing impacts on pasture, dairy production and farm finances after several years of climate-affected extremes.

A preview of a hotter normal

Climate records kept by the Bureau of Meteorology show Australia has warmed by about 1.5 to 1.55 C since 1910. The agency’s most recent annual statements list 2024 as the country’s second-warmest year on record and 2025 as the fourth-warmest, with all months in 2025 warmer than the 1961–1990 average.

An international group of scientists working with the World Weather Attribution initiative recently analyzed an earlier phase of January’s heat in Australia. Their rapid study concluded that human-driven climate change had made such heatwaves around five times more likely and increased their peak temperatures by about 1.6 C compared with a pre-industrial climate.

Researchers involved in that work have warned that if global warming reaches around 2.6 C above pre-industrial levels, severe heatwaves of the kind seen this month could occur every two years on average instead of being rare events.

For now, residents across southeastern Australia are watching thermometers drop as a cooler change moves through, bringing relief and, in some places, renewed wind-driven fire risk.

In Gellibrand, generators still hum beside blackened forest as tankers top up emergency water supplies. In Melbourne’s suburbs, the return of the refrigerator’s buzz and the sigh of an air conditioner signal a return to normal daily life.

But for many who endured days of 40-plus heat, bushfire smoke and unexpected blackouts, the week has left a lingering question: if this is what a 1.5-degree world looks like, how ready are Australia’s systems for the next time the mercury climbs toward 50?