Newly released cabinet documents from 2010 show the government was warned high fire danger days would increase from 23 to 36 a year by 2050, and extreme heat would pose risks to children, the elderly and sick.

In a summary of key findings presented to cabinet by the then planning minister, Andrew Barr, the government was warned the number of 40-degree days would grow from an average of none in a warming scenario of 2 degrees by 2050.

But the cabinet was advised the ACT was on track for a warming scenario greater than 2 degrees.

Canberra broke its record for the number of days in a row above 40 degrees in January 2019, with four days of extreme heat in a row.

For 25 years between 1973 and 1998, Canberra did not record a single 40 degree day.

There were nine days that reached 40 degrees between 1913 and 2006. There have been 19 in Canberra since 2009.

Cabinet noted the study, prepared by consultants AECOM, in October 2010.

The study warned the number of days available for prescribed burns "may be affected" and recommended calculating different fire danger ratings for different parts of the ACT.

The bushfire fuel hazard around Black Mountain and Bruce Ridge would grow from mostly very high to extreme by 2019.

The study said there would be up to 21.5 days a year over 35 degrees in Canberra, up from just five annually, while rainfall would decrease between 5 and 18 per cent.

The number of very high to extreme forest fire danger index days could rise to 36 annually, up from 23.

"Heatwave is the most significant threat, given both the frequency of its predicted occurrence and the fatalities [and] serious illness that result," cabinet was told.

"This has important implications for future urban form , especially in regard to density and urban heat island effects, which are currently poorly researched in Canberra."

MORE A.C.T. CABINET DOCUMENTS:

The study said: "Vulnerability is not solely dependent on physical proximity to the source and intensity of the hazard, but also on the interconnectivity among social, cultural and economic influences and biophysical factors.

"Neighbourhood as well as household level influences ... are critical to understanding vulnerability."

The perceptions of extreme heat risk, based on exposure at home, work or during recreation, needed to be better understood to map out how easily the territory could adapt, the study said.

The government was also warned ageing stormwater infrastructure would be a limitation and the approach for new stormwater systems may need to be revised.

In the years since, the ACT government has earmarked significant funding for improving the city's stormwater network.

The ACT government also released a climate change strategy in 2019, which identified emissions reduction priorities and options to reduce waste and improve urban heat resilience.

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