Heat, humidity, and the El Niño – Southern Oscillation in Sydney, Australia

Abstract

High temperatures and humidity are known to significantly impact human health and wellbeing across Australia, although few studies have investigated the localised climatology of such events. In this paper, a number of indices of extreme heat and humidity are investigated in Sydney, Australia, providing an overview of the frequency and trends of such events across the city. Although summer average temperatures have consistently increased over the past fifty years, no statistically significant trend is observed for extreme temperatures and heatwaves in Sydney, with interannual variability a stronger influence on such events. In particular, hot days and nights are most likely to occur during El Niño years, but also where local sea surface temperatures are anomalously warm, which is most common during La Niña years. The relative importance of local and global variations in sea surface temperatures for air temperatures in Sydney is an interesting area for future research, particularly with respect to the strong warming trend observed in coastal sea surface temperatures around Australia.