Heatwaves are a hallmark of an Australian summer. But they're getting hotter, becoming more frequent, and lasting longer.

Sydney and Melbourne could experience 50C summer days before the end of the century if greenhouse gas emissions continue to rise, a new report highlights.

The Climate Council’s report said more than 206 heat records had been broken in just 90 days this year including record-highest temperatures in 87 locations.

In NSW, temperatures are 3.41C above average.

“Queensland and New South Wales have both lost more homes (to bushfire) since August 2019 than in any previous year, with the hottest months of the fire season still to come,” the report said.

Recent bushfires have also created a health hazard in cities like Sydney, which were covered in smoke haze for several days.

Dr Kate Charlesworth said air quality had been impacted so badly in some areas, “it’s the equivalent of smoking 40 cigarettes a day”.

In Australia, the main risk to human life from climate change arises from heatwaves, which can lead to illnesses like heat exhaustion and the worsening of heart and kidney disease.

“Climate change is a serious health issue. Health professionals like myself have a duty to speak up just as we did with asbestos and tobacco,” Dr Charlesworth said.

Heatwaves, defined as at least three days in a row of unusually high temperatures, are occurring more frequently in Australia.

They now start 19 days earlier in Sydney and 17 days earlier in Melbourne if you compare the data for 1981-2011 and 1950-1980.

The number of heatwave days each year has also increased in Perth, Adelaide, Melbourne, Sydney, Canberra and Hobart since 1950.

The hottest day of the heatwave is also becoming hotter.

Most dramatically, the peak day in Adelaide is on average now 4.3C higher in 1981-2011 compared with 1950-1980.

The report noted Sydney and Melbourne could experience 50C summer days by the end of the century.

Drought is also an issue, with the central west of NSW facing a dangerous summer.

The period from January 2017 to October 2019 has been the driest on record for the Murray-Darling Basin as a whole.

The current prolonged drought across eastern Australia is threatening crops for the third year in a row, and national summer crop production is forecast to fall by 20 per cent to 2.1 million tonnes in 2019/20.

“Major regional centres such as Orange and Dubbo are currently facing severe water shortages, and this summer is shaping up as a terrible trifecta of heatwaves, droughts and bushfires with no reprieve for the Central West,” Climate councillor and report author Professor Will Steffen said.

“We have seen bushfires starting in winter, a heatwave traversing the country in spring, and a prolonged drought. Climate change is influencing all of these things,” Prof Steffen said.

Rob Lee, a beef and sheep farmer in Larras Lee, northwest of Orange, said he had been anxious about the changing climate for more than 15 years, which is why he joined Farmers for Climate Action.

“We can see the conditions changing out here. We have less rainfall, winters are getting drier, the surface water is no longer reliable and dams are drying up,” Mr Lee said.

“We have never seen a drought as bad as this. In 2018, we sold one-third of our cows, and again this year we sold another third. Once we are through the next calving, we will get out altogether and run just sheep.

“We have also built drought lots to contain our sheep. This protects the topsoil which can turn to dust in the dry conditions.

“We have made a number of changes to our farming practices, but if climate change continues to accelerate, driving more drought conditions, it is going to be very hard to make a living as a farmer.

“Australia needs to take serious, credible action on climate change. Renewable energy is an investment in the future, an opportunity that could create a lot of industries in regional areas like the Central West,” Mr Lee said.

The Bureau of Meteorology is forecasting above-average maximum temperatures for most of Australia this summer with eastern Australia likely to be drier than average.

“This long-term warming trend driven by the burning of coal, oil and gas is putting Australian lives, our economy and the environment at risk,” Climate Council chief executive officer Amanda McKenzie said.