Most regions of Australia are exposed to hot summers and regular extreme heat events; and numerous studies have associated high ambient temperatures with adverse health outcomes in Australian cities. Extreme environmental heat can trigger the onset of acute conditions, including heat stroke and dehydration, as well as exacerbate a range of underlying illnesses. Consequently, in the absence of adaptation, the associated mortality and morbidity are expected to increase in a warming climate, particularly within the vulnerable populations of the elderly, children, those with chronic diseases, and people engaged in physical labour in noncooled environments. There is a need for further research to address the evidence needs of public health agencies in Australia. Building resilience to extreme heat events, especially for the most vulnerable groups, is a priority. Public health professionals and executives need to be aware of the very real and urgent need to act now.