Increasing risk of months with low rainfall and high temperature in southeast Australia for the past 150Â years

Climate variability, climate change and extreme events pose risks that need to be quantified and managed. Dry and hot conditions have notable impacts, and have a strong link to drought risk. Many extreme event analyses focus on one variable at a time. However, compound extremes, involving two or more climate variables, can have a disproportionately large impact. Thus integrated multivariate analyses are necessary to comprehensively assess climate impacts. Here we document 150 years of information about events with low monthly rainfall and high temperature for southeast Australia. The number of hot/dry months per year exhibits decadal variability and increasing trends. Long-term trends are more influenced by temperature than rainfall, consistent with a warming climate. The number of hot and dry consecutive events, defined as three to five consecutive months of compound events, is increasing. Our findings reinforce the need to consider definitions that include multivariate variables such as rainfall and temperature and/or other hydroclimate variables, where possible, when quantifying drought risk. Discussion on how the results could contribute to improvement in climate projection science in Australia or elsewhere is provided.