Mt Lawley and Mt Hawthorn are just a few kilometres apart but on a hot day the temperature difference between the urban centre and the residential neighbourhood is palpable.
According to readings taken by _The West Australian _yesterday, Mt Lawley was 5C hotter than its more leafy counterpart during the middle of the day, illustrative of research which found Perth's built-up areas were more vulnerable in heatwave conditions.
A Monash University study, which maps suburbs according to heat vulnerability, revealed that the northern suburbs of Wangara, Stirling, Morley, Menora and Mt Lawley were most "at-risk".
Rivervale, Como, Booragoon and Bibra Lake were identified as the most vulnerable suburbs in the south.
The study found that people living in these suburbs were most susceptible to heat-related illness and death in extreme temperatures.
Nigel Tapper, from Monash's Co-operative Centre for Water Sensitive Cities, said heat vulnerability of specific suburbs was assessed on environmental risk factors including lack of tree cover, housing type and urban design as well as on social factors such as age of residents and socio- economic status.
Professor Tapper said research could help emergency response planning during heatwaves and also be used to guide future urban planning.
"There is a clear association between suburbs with extreme heat vulnerability and the number of hospital emergency visits or ambulance call-outs on extremely hot days," he said. "In areas covered by buildings, urban warming occurs that can increase local temperatures about 4C. "This can take the temperature over the threshold where human health is threatened."
Professor Tapper said Perth's threshold was higher than most other capital cities because West Australians were more acclimatised to the heat.
Yesterday, when the average metropolitan maximum temperature in Perth hovered around 37C, it was 40C on Beaufort Street in Mt Lawley and 35C in Mt Hawthorn on The Boulevarde. Professor Tapper said a few degrees atmospherically could make a big difference to body temperature.