Lethal Heating: 01/27/26

Key Points

January 2026 delivered one of Australia’s most intense and widespread summer heatwaves in years, supercharged by human-driven climate change ¹
Extreme heatwaves are now hotter, longer and more frequent across Australia, and climate change has made the latest events several times more likely ²
The January heat pushed fire danger to extreme and even catastrophic levels in parts of south-east Australia, with large bushfires in Victoria ³
Heatwaves are Australia’s deadliest natural hazard, driving spikes in hospital admissions and straining power, transport and workplace safety ⁴
Rising temperatures are reshaping rivers, water security and ecosystems from the Murray–Darling Basin to northern Australia’s wetlands ⁵
Without rapid emissions cuts and serious adaptation, Australian agriculture, energy systems and cities face escalating heat risks ⁶

Before dawn in Mildura, the air already feels spent, as if the sun has been up for hours, and residents are bracing for yet another day above 40C in what has become a week-long siege of heat across south-eastern Australia.¹

From inland South Australia to western New South Wales and Victoria, maximum temperatures have climbed into the mid to high 40s, part of a severe to extreme heatwave that forecasters say may break long-standing records in multiple locations.¹

Along the north-west coast of Western Australia, temperatures near 50C earlier in January set new local January records and came close to Australia’s all-time highs, underlining how little room remains before physical limits are reached.¹

At the same time, authorities in Victoria declared a state of disaster as hot, dry winds and parched fuels drove fast-moving bushfires that burned hundreds of thousands of hectares.³

Climate scientists now say the early-January heatwave that set the stage for these fires was made around five times more likely by human-caused global warming, compared with a pre-industrial climate.²

Hospitals and emergency services have reported spikes in heat-related admissions, while power demand for cooling has surged and outdoor work has become dangerous in many regions.²

For many Australians, the January 2026 heat is not just another uncomfortable spell, it is a clear sign that climate change is reshaping the country’s summer and magnifying the risks that come with extreme heat.²

How climate change drives extreme Australian heat

Climate change increases extreme heat in two main ways: it raises the average temperature, and it alters weather patterns in ways that make heatwaves more intense and persistent.⁷

The Intergovernmental Panel on Climate Change and multiple Australian studies have found that human greenhouse gas emissions have warmed the continent by about 1.4C since 1910, meaning that heatwaves now develop on a much hotter baseline than they did a century ago.⁷

A landmark analysis of Australian heatwaves by the Climate Council, drawing on Bureau of Meteorology data, shows that heatwaves have become hotter, longer, more frequent and are occurring earlier in the season since the 1950s.⁸

This trend is consistent with global attribution studies that compare the real world with modelled worlds without human emissions to determine how much climate change has altered the odds of extreme events.⁹

In January 2026, those background changes combined with short-term weather drivers to produce exceptional heat.¹

A strong, slow-moving high-pressure system over Western Australia generated sinking, drying air that allowed temperatures in the north-west to climb close to 50C, before that heat was transported east across the continent by hot north-westerly winds.¹

From 5 to 10 January, south-eastern Australia recorded its most severe heatwave since 2019–20, with temperatures above 40C in major population centres and prolonged periods of high overnight temperatures that prevented homes and infrastructure from cooling down.²

An attribution analysis released in late January concluded that this early-January event was roughly five times more likely because of anthropogenic climate change and would have been significantly cooler in a pre-industrial climate, even with the same large-scale weather pattern.²

CSIRO’s event attribution work has found similar human fingerprints on previous Australian heatwaves, including record-breaking events in 2013 and 2019, reinforcing the conclusion that climate change is now the dominant driver of extreme heat risk in Australia.⁹

The geography and physical character of the January heat

The January 2026 heatwave has not been a single, uniform event but a rolling sequence of extreme conditions affecting different regions in turn.¹

In the first half of the month, the focus was on Western Australia’s north-west, where Shark Bay recorded a new January record near 49C and Carnarvon reached its hottest January day on record at about 48C under a stagnant upper high.¹

As this heat dome shifted east, inland South Australia, western New South Wales and north-west Victoria endured days on end above 40C, with forecast peaks up to 48C in the Murraylands, Riverland, Mallee and lower western districts of New South Wales.¹

Cities such as Adelaide and Melbourne saw temperatures rebound into the low 40s on multiple days as relief from weak cool changes failed to reach far inland, trapping hot air over the interior.¹

These conditions translated directly into heightened bushfire danger.¹

In South Australia, soil moisture levels were already extremely low after several years of below-average rainfall, meaning fuels were dry and highly flammable.¹

As hot, dry north-westerly winds strengthened, fire danger ratings climbed to extreme in many districts and were forecast to reach catastrophic on the Yorke Peninsula, a level associated with fast, unpredictable fires that can overwhelm even well-prepared homes.¹

In Victoria, strong winds and severe heat helped several fires burn out of control, ultimately scorching more than 400,000 hectares and destroying hundreds of structures, including homes, prompting a state of disaster declaration.³

CSIRO and the Bureau of Meteorology have previously projected that climate change will increase the number of days with extreme fire danger by 5–25 per cent by 2020, relative to 1990, for a modest 0.4C of global warming, suggesting that risks will continue to escalate as temperatures climb further.¹⁰

Heat, health and the economy

Heatwaves already kill more Australians than any other natural hazard, and January 2026 has underlined why health experts describe extreme heat as a “silent emergency”.⁸

A 2025 scoping review of extreme heat and health in Australia found strong evidence that hot days and heatwaves increase deaths and hospitalisations from cardiovascular disease, diabetes, respiratory illness and mental health conditions, particularly among older people, those with chronic disease and people in low-quality housing.¹¹

The review reported, for example, that people with kidney disease in the Northern Territory faced a 29 per cent higher risk of heat-associated hospitalisation during extreme heat, and that heatwaves were linked to higher rates of stroke admissions in Brisbane.¹¹

During the early-January 2026 heatwave, one major hospital reported a 25 per cent jump in emergency department presentations, highlighting the stress that even a single event can place on the health system.²

The economic impacts of extreme heat are similarly broad but less visible.¹¹

The same 2025 review noted estimates that more than 10 million Australians are exposed to hazardous heat, with potential losses of about $211bn in agriculture and labour productivity by 2050 under current warming trajectories, as well as large projected losses in the property sector from climate extremes including heatwaves.¹¹

January’s heat has already affected productivity by forcing outdoor work to pause during the hottest hours, increasing cooling costs for households and businesses, and adding pressure to electricity networks as demand for air conditioning surged.²

In some regions, authorities issued public health alerts urging people to stay indoors, check on neighbours and limit physical activity, measures that are essential for safety but that also curtail economic activity and social life.²⁰

Ecology, wildlife and culture under stress

Australia’s plants and animals are adapted to heat and fire, but the intensity and frequency of recent heat extremes are pushing many species beyond their limits.¹²

Previous heatwaves have caused mass deaths of flying foxes, fish kills in inland rivers and coral bleaching on the Great Barrier Reef, and scientists warn that similar impacts are likely when air and water temperatures spike for prolonged periods.¹³

The January 2026 heat has coincided with high fire danger across forested regions of south-eastern Australia, raising the risk of habitat loss for species still recovering from the 2019–20 Black Summer fires.³

CSIRO has noted that hotter, longer fire seasons and more frequent extreme heat will make it harder for ecosystems to recover between disturbances, leading to shifts in species composition and, in some cases, permanent loss of biodiversity.¹⁰

These changes also carry deep cultural consequences.¹⁴

First Nations communities whose traditions are tied to specific landscapes, seasonal cycles and species face the prospect of losing key cultural practices as fire regimes, water availability and wildlife distributions change.¹⁴

In some regions, extreme heat has already disrupted community events, ceremonies and sporting fixtures, with summer activities cancelled or shifted to early morning or night to avoid dangerous conditions.²⁰

For many Aboriginal ranger groups, intense heat waves can limit the window for cultural burning and land management work, even as the need to reduce fuel loads and manage Country becomes more urgent in a warming climate.¹⁴

Heat, rivers and water security

Extreme heat does not operate in isolation from Australia’s water systems; it interacts with rainfall, evaporation and land management to shape river flows, water quality and the security of supplies for towns, farms and ecosystems.¹⁵

In the Murray–Darling Basin, which supports much of the country’s irrigated agriculture, higher temperatures increase evaporation from rivers, dams and soils, reducing the efficiency of rainfall and increasing the risk that moderate dry spells turn into severe droughts.¹⁶

During intense heatwaves, low, slow-moving rivers can warm rapidly, reducing dissolved oxygen levels and raising the risk of hypoxic fish kills, particularly when combined with nutrient run-off or sudden changes in flow.¹⁶

Heat also increases water demand from irrigators, towns and ecosystems at the same time as supply is constrained, a tension that plays out in water markets and environmental flow decisions long after the immediate event has passed.¹⁶

Northern Australia’s wet-dry tropics face a different but related set of challenges.¹⁷

Projections suggest that while total wet-season rainfall may not decline strongly in some northern basins, higher temperatures will increase potential evaporation and may shorten the period of high flows, concentrating ecological stress into longer, hotter dry seasons.¹⁷

Wetlands and floodplains that depend on seasonal inundation, including culturally significant sites for Indigenous communities, become more vulnerable when extreme heat accelerates drying between floods.¹⁷

For remote communities that rely on shallow groundwater or small surface storages, heatwaves can also worsen water quality by promoting algal growth and increasing the concentration of contaminants as volumes drop, adding to existing infrastructure and health challenges.¹⁵

Long-term implications for key sectors

The conditions Australians have faced in January 2026 are consistent with what climate models project will become far more common unless global emissions fall steeply.⁷

Under a high-emissions scenario, much of inland Australia could experience several additional weeks per year of days above 35C by mid-century, with large increases in the number of days above 40C, particularly in already hot regions.⁷

For agriculture, this means more frequent heat stress on crops and livestock, reduced yields during key growth stages and increased irrigation demand at the same time that water resources are under strain.¹⁸

CSIRO has warned that without adaptation, heat and water stress will erode productivity in sectors such as grains, cotton, dairy and horticulture, and could force shifts in where some industries are viable.¹⁸

For the energy sector, rising temperatures create a dual challenge of soaring demand for cooling and reduced capacity of some generation and transmission assets to operate in extreme heat.¹⁹

Coal and gas plants can become less efficient at high temperatures and may face cooling water constraints during drought, while transmission lines can carry less power when air temperatures are very high, increasing the risk of blackouts during heatwaves.¹⁹

At the same time, distributed rooftop solar performs well during sunny heatwaves, although output can dip slightly on the hottest days, and storage and demand management will be critical to smoothing evening peaks when residual heat lingers but solar generation falls.¹⁹

Urban planning will also need to confront a much hotter future, as more frequent days above 35C make existing housing, transport systems and public spaces increasingly uncomfortable and, at times, unsafe.¹⁸

Strategies such as tree planting, reflective surfaces, better building insulation and design, and accessible cool refuges will be central to reducing urban heat islands and protecting vulnerable residents.¹⁸

What planners and policymakers must do now

For regional planners and policymakers, January 2026 is less a surprise than a stress test for systems that were largely designed for a cooler climate.⁷

The first priority is rapid emissions reduction, because every fraction of a degree of additional warming will compound the risks of extreme heat, bushfire, water insecurity and ecosystem loss documented by Australian and global assessments.⁷

In practice this means phasing out coal and gas power, supporting the rapid build-out of renewables and storage, and integrating heat risk explicitly into national and state climate targets and sector plans.¹⁹

At the same time, governments must treat extreme heat as a core planning constraint, not a seasonal inconvenience.⁸

Heat-health action plans that identify vulnerable populations, establish cool refuges, set work and school protocols, and improve housing quality can reduce deaths and illness, but they need consistent funding and coordination across health, housing, education and workplace safety agencies.¹¹

Land-use and bushfire planning should incorporate the latest projections of fire weather and extreme heat, limiting development in the most exposed areas and strengthening building standards, evacuation routes and early warning systems.¹⁰

Water planning in basins such as the Murray–Darling must assume higher evaporation and more intense heatwaves, securing environmental flows and town water supplies under a hotter, drier climate, while involving First Nations communities in decisions about Country and cultural water.¹⁶

The January 2026 heatwave shows that Australia still has choices: the more decisively it cuts emissions and designs for a hotter world, the less brutal its future summers are likely to be.²

References

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27/01/2026

January 2026: a brutal preview of Australia’s hotter future - Lethal Heating Editor BDA