It is well known that you do not feel the same on a sunny day in Darwin with 27°C than a clear sky day in Melbourne with the same temperature. While it might be a sticky day for runners in the tropics, exercising outside in Victoria’s capital could be quite pleasant. This is because air temperature alone is not necessarily the best indicator of environmental conditions conductive to heat stress on human health. Hot temperatures with high humidity reduce the ability of the human body to dissipate metabolic heat, leading to increased body core temperature. It is, therefore, the combination of heat and humidity that really matters. Wet-Bulb Globe Temperature (WBGT) estimates the effect of temperature, humidity, wind speed and solar radiation on humans and is one of the most widely used and validated index for assessing the environmental heat stress. For instance, the ISO standard for heat stress uses WBGT to recommend work-rest limits for work in hot environments in order to ensure that average core body temperatures of worker populations do not exceed 38°C. In addition to the US and UK military, the WBGT value is used as a heat index in many sporting situations to determine the impact of environmental temperature, such as at the Australian Tennis Open. In spite of the increasing interest in WBGT, only a few studies in Australia have been performed to date. This study presents a detailed climatology of WBGT in Australia by using reanalysis and observations. Furthermore, the WBGT trend over the last 4 decades in several Australian regions is analyzed. Finally, the dependency of the calculated WBGT on the approximation of black-globe temperature (BGT), one of the key components of WBGT, is also examined.