Households without the means to install or run air conditioners are on track to suffer through far more hot days in its "high" emissions scenario.
The world is headed towards more moderate warming than the most emissions-intensive pathway modelled by the Climate Council, but the non-profit group's chief executive Amanda McKenzie said such a scenario was possible if countries fail to cut back on fossil fuels.
US President Donald Trump's 'drill, baby drill' attitude was a recipe for "climate chaos", Ms McKenzie said.
"Let's be clear: 'drill, baby, drill' means Australian suburbs will grill, baby, grill," she said.
A heat map showing electorates most vulnerable to extreme temperatures has been released ahead of a federal election that must be held by May 17.
The major parties have vastly different visions for the energy system, with Labor pursuing a renewables-led transition while the coalition wants to build nuclear power plants.
The Climate Change Authority released modelling showing the nation could miss the legislated 43 per cent emissions reduction target for 2030 by taking the nuclear pathway.
Lower-income electorates such as Blaxland and Fowler in Sydney's west could expect decent increases in hot days.
Under the existing policy pathway, the latter was tipped to experience 18 days a year above 35C by 2090, an increase of nine days.
That figure shot up to 31 days a year under the high emissions scenario.
Regional electorates in the already-hot northern states face particularly sharp increases in extreme heat days under the high emissions scenario.
Maranoa in southwest Queensland would swelter through 172 hot days annually, an almost two-fold increase from current averages.
Coastal breezes should insulate wealthier seaside electorates from the worst of the heat but Ms McKenzie said no area was immune to climate risks, especially suburbs prized for their proximity to bushland.
"The Los Angeles fires are a powerful reminder of how vulnerable cities can actually be to extreme weather," she told AAP.
Regions with large elderly populations were also found to be at higher risk from extreme heat.
Kate Charlesworth, public health physician and councillor with the Climate Council, said older people were particularly vulnerable to hot weather as the ability to keep cool by sweating diminishes at age 65 and over.
Older Australians tend to have other health complications, compounding vulnerability, she added.
Dr Charlesworth said the human body was typically "working pretty hard" to stay cool at 37C, noting that humidity, wind and other factors alter the experience of hot weather.
"Once you get about 39C, 40C or 41C, you're getting into heat exhaustion territory and then heat stroke," she told AAP.
The elderly, pregnant women and babies and children were the most vulnerable but everyone was at risk on hot days, especially those working outside or exercising.
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