Australia Weather News

A study has found Adelaide and Melbourne residents are most at risk during a heatwave. - ABC

Adelaide and Melbourne are among the most dangerous Australian capital cities to live in during the summer months, with residents more at risk of death during an extreme heatwave, a recent study has found.

While those residing in Australia's east-coast capitals such as Brisbane and Sydney may feel they are challenged most by the heat, the study has found they were less likely to be caught out by an extreme heatwave.

Thomas Longden, a researcher from the University of Technology Sydney (UTS), said his findings suggested people in the east-coast capitals tended to acclimatise to the heat better.

But it was a different story for those residing in Adelaide, Melbourne and Perth.

"While Sydney and Brisbane have hot summers, most of their summer days tend to be of a similar temperature and this assists people to acclimatise to the heat," Dr Longden said.

"In Melbourne, Adelaide and Perth however we have had extreme heatwave events with three-day average temperatures spiking up to 12 degrees Celsius above the 30-day average."

He said these abnormal events were rarer in Sydney and Brisbane and were more likely to catch out people who were unprepared for the extreme heat.

Melbourne has most deaths but Adelaide hit hardest

Daily temperatures and mortality data from the Australian Bureau of Statistics and the Bureau of Meteorology was used in the study, focusing on the timeframe between 2001 and 2015.

The study found that the number of deaths due to heatwaves in Australia's five largest capital cities during that period was highest in Melbourne, followed by Sydney, Adelaide, Perth and Brisbane.

Melbourne recorded 1283 deaths, Sydney had 768, there were 549 recorded in Adelaide, Perth had 532 and Brisbane had the least with 220.

But when the statistics were broken down — on a per capita basis — Adelaide was the hardest-hit capital city, followed by Melbourne and Perth.

Dr Longden said the study used an index which captured a lack of acclimatisation to hot temperatures.

It did this by tracking the difference between the three-day average temperature and the 30-day average temperature in each capital city.

"This measure captures heatwaves where people have difficulty acclimatising or adapting to the heat because it is extremely hot compared with the previous 30 days," he said.

He said the findings explained why some of the most deadly heatwaves occurred in regions such as Melbourne and Adelaide; the cities tend to have more moderate average temperatures and residents do not adapt as well to an abrupt temperature increase.

Record temperatures spike across Australia

The study found that the largest number of deaths occurred when the three-day average temperature was more than 7C above the 30-day average.

Between 2001 and 2015, Melbourne and Adelaide had days where the index used was above 12C, with one of the hottest heatwave events occurring in Adelaide between January 27 and 30 of 2009.

The Bureau of Meteorology found that in 2009, Adelaide had 10 days of temperatures above 35C. The hottest maximum temperature recorded in Adelaide was 45.8C on January 28 at Edinburgh.

Similarly in Melbourne, temperatures were above 43C for three consecutive days from January 28-30 in 2009.

Another heatwave was recorded in Melbourne during 2014 with temperatures above 41C between January 14-17.

Dr Longden said he hoped the findings would have implications for the type of weather events that should trigger heat health alerts.