Western Sydney is on track to experience five times the number of extreme heat days a year if something is not done to curb emissions.
In a high-emissions scenario Penrith could face up to 58 days, or two months, of extreme heat in a year, a report from the Australia Institute has found.
The report models how hot it's likely to get in western Sydney electorates in coming decades, with Penrith, the federal seat of Lindsay, forecast to have the most days over 35 degrees.
In 2050, people living in Penrith could be sweltering through more than a month of 35-degree-or-hotter days in a high emissions scenario - and by 2090 that would increase to 58 days a year.
That prediction could be cut to 22 days a year if emissions are reduced.
But real-world figures have already outstripped these projections, with Lindsay reporting 44 days over 35 degrees in both 2018 and 2019.
That number, 44 days of over 35 degrees, exceeds the projected average for 2090 of 42.5 days - 70 years ahead of schedule.
Climate & Energy Program Director at The Australia Institute, Richie Merzian, says western Sydney's extreme heat problem will "only be exacerbated as global warming drives up the frequency and intensity of extreme heat events".
Children growing up west of the city could see the number of dangerously hot days "quadruple by the time they retire", he said.
That outcome was not inevitable and many of the predicted outcomes could be avoided by successive governments adhering to the Paris Agreement.
Executive Director at Sweltering Cities Emma Bacon said extreme heat should be considered a "public health emergency" as increasing temperatures put more people at risk.
Different communities dealt with different temperatures and some people had to work outside, while others did their jobs in heavy PPE, she said.
The HeatWatch Report from the Australia Institute Climate & Energy Program was produced in partnership with Sweltering Cities and used modelling from the CSIRO and BOM to show how western Sydney is particularly vulnerable to extreme heat.
The area, at the base of the Blue Mountains, is insulated from cooling breezes and is a sink for hot air - a situation that has been compounded by removal of green spaces and bee replaced with concrete and asphalt.
Some suburbs in western Sydney routinely record temperatures about eight to 10 degrees above eastern Sydney.
