There are numerous studies that have estimated the number of deaths attributable to heat and cold using city-level or provincial-level data. However, none of these studies have assessed temperature-mortality relationships using meteorological climate zones and data that covers an entire population/country. This analysis uses a national data set of death records to create time-series data for different regional aggregations. Temperature-mortality relationships are estimated using this data set of 1,717,224 deaths, which covers the whole of Australia between 2006 and 2017. This paper finds that the majority of deaths related to temperature in Australia are caused by heat. It also finds that the reference temperature used to separate impacts into heat-/cold-related mortality has a notable impact on the magnitude of these estimates. Previous studies (using the same methodology) found that most of the temperature-related mortality burden in Australia was attributed to cold temperatures. This led to studies that associated this with a net benefit from climate change. This analysis indicates that studies that found net benefits from climate change need to be re-assessed, especially for Australia and warmer climate zones.