Canberra has experienced its longest run of days above 40 degrees, with the temperature hitting 40.1 at 3.41pm on Friday afternoon, while experts say the city needs to quickly adapt to more extreme heat driven by climate change.
A cool change is expected to bring closer to average temperatures on Friday night or early on Saturday morning – but the capital still sweltered through four days at 40 degrees or above, the worst heatwave since January 1939.
Bureau of Meteorology Senior Climatologist Blair Trewin said the current heatwave was striking to people of his generation who grew up in Canberra and never experienced a day above 40 degrees.
For 25 years between 1973 and 1998, Canberra did not reach 40. There were nine days where temperatures reached 40 degrees between 1913 and 2006, but since 2007, Canberra has reached 40 degrees 16 times, including Friday.
The hottest day recorded at Canberra Airport was 42.2 degrees on February 1, 1968. An earlier observation site at Acton, now beneath Lake Burley Griffin, recorded 42.5 degrees on January 11, 1939.
"We haven't seen that many individual day records broken in this heatwave," Mr Trewin said.
"It's main significance is its length. The only comparable one is the heatwave is of January 1939."
A "weak cool change" is forecast to bring cooler temperatures late on Friday night or early on Saturday morning.
"Temperatures are still going to be in the low 30s."
Wednesday was the hottest day this week. Tuesday reached 40.1 degrees, Wednesday reached 41.6, Thursday reached 41.4 and Friday reached 40.1.
The heatwave placed higher demands on the ACT's electricity grid this week, but supply shortfalls, which would have seen rolling blackouts in the capital on Friday to manage electricity demand, did not eventuate.
The director of the Climate Change Institute at the Australian National University, Mark Howden, said a particular heatwave wasn't a direct result of climate change, but climate change was embedded into all extreme weather events.
Professor Howden said a small increase in the average temperature meant a higher likelihood of hotter temperatures.
There was only a five degree average temperature difference between present climate conditions and the Ice Age, he said.
Canberra could expect extreme hot weather more frequently and in longer spells, along with a reduction in autumn, winter and spring rainfall, Prof Howden said.
"We'd also expect to see a lot more fires and fire frequency, and the fire season and the intensity of those fires going up."
"Canberra is probably one of the more climate change aware and climate change active cities and that's particularly because the current government has been leaders in terms of climate change," Professor Howden said.
The ACT government's 2016 Climate Change Adaptation Strategy requires the impacts of climate change to "mainstreamed" and incorporated into government, household and business practice.
Dr Peter Tait, an Australian National University lecturer and general practitioner who spent 32 years in Alice Springs, said many of his Canberra patients didn't have heatwave contingency plans and that needed to change as the city experienced more periods of extreme heat.
But Dr Tait said the emphasis needed to be on building heat resilience into the "fabric of society", including enforcing heat appropriate building codes.
"We need to be doing that active infrastructure planning now," he said.
"We know that over the next 50 to 60 years, which is about the average lifetime of a house, we're going to get one degree warmer, which means on average we'll go from 38 degree days to 42 degree days."
Dr Tait said the best time to implement these changes was "yesteryear", and there was now a smaller margin of error for making widespread changes.
"The rate which we must change is much steeper and we have much less buffering in the system," he said.
"I’m pessimistic but hopeful. We don’t know we’ve lost yet, so we need to keep struggling because if we give up we will lose."
In 2017, a CSIRO report found that the effects of climate change in Canberra's urban areas would create a growing risk of heat-related illness in the city.
But cold winters required planners to ensure measures introduced to reduce the impact of heatwaves didn't "exacerbate" cooler conditions in winter.