Research undertaken by Risk Frontiers shows that heatwaves are responsible for more deaths in Australia than from all other natural disasters put together (heatwaves-paper_coates-haynes-et-al_2014). With this in mind, Dr Thomas Loridan has defined five new heatwave fatality risk categories. These categories capture conditions that lead to higher numbers of deaths and acknowledge that the most dangerous events are those characterised by both large peak intensity and a sustained period of severe heat. Category maps for major historical or simulated events can be overlaid with population to calculate death rates by annual return interval. Loridan, T., Coates, L., Argüeso, D., Perkins-Kirkpatrick, S.E. and J. McAneney (2016). The Excess Heat Factor as a metric for heat-related fatalities: defining heatwave risk categories, Australian Journal of Emergency Management, vol 31, no. 4.