On the recent hiatus of tropical cyclones landfalling in NSW, Australia

It is well known that severe storms result in some of the costliest natural disasters for New South Wales (NSW), Australia. However, it is not widely acknowledged that some of these events are, in fact, a result of landfalling tropical cyclones (TCs). Indeed, the intense focus of TC research within the tropics generally disregards landfalling TC events in the mid-latitude regions of Australia. This is likely due to the perceived infrequency of these events compared to other more susceptible regions. Therefore, in this study, we review this assumption by developing a 150-year record of TC activity, based on a range of digitised and analogue historical datasets and identify 30 individual landfalling TCs that have impacted NSW. Periods of enhanced and reduced TC activity are observed, with a defined hiatus (absence of landfalling TCs) after approximately 1980. The recent decrease in TC activity is subsequently linked to an increase in El Niño activity and warming of north-west Australian sea-surface temperatures during this time. Importantly, it is possible that a return to enhanced TC activity could occur again in the future if the Pacific conditions align. We also propose that pre-instrumental data on TC activity need to be developed to appropriately quantify TC risk for the study region via the development of local palaeoclimate archives. This study provides a significant contribution to understanding the risks of NSW landfalling TCs and expands upon our knowledge of environmental conditions that influence landfalling TCs in NSW.