Global temperature increases are most clearly detected in the shifting distribution of extreme events. Australia’s warming climate has resulted in significant changes in the frequency of temperature extremes, with a general increase in heatwaves and a reduction in the number of cold days. Here, we present the longest historical analysis of daily Australian temperature extremes and their societal impacts compiled to date. We use a newly consolidated early instrumental dataset and a range of historical sources for the South Australia region of Adelaide—the nation’s driest state, containing the most heatwave-affected city in Australia—to investigate any changes in the characteristics of daily temperature extremes back to 1838. We identify multidecadal variability in heatwave and snow event frequency with a peak in the early twentieth century, with an overall decrease in cold extremes and an increase in heatwaves in the region over the 1838–2019 period. Documentary and instrumental records show a decrease in the number of snow events in Adelaide, and a clear increase in the number of heatwaves since the late twentieth century. To gain dynamical insight into historical extremes in South Australia, detailed case studies are presented to compare the synoptic characteristics of historical hot and cold extremes and their impacts. We place a particular emphasis on lesser-known events of the pre-1910 period and rare low-elevation snowfall. Significantly, this is the first study to provide long-term evidence for a reduction of low-elevation snow events and cold outbreaks in Australia. Finally, a discussion is provided on the value and limitations of using historical instrumental and documentary data to assess long-term changes in Australian temperature extremes and their potential to improve future climate change risk assessment.

在极端事件的变化分布中最清楚地检测到全球温度升高。澳大利亚的气候变暖导致极端温度的频率发生了重大变化，热浪普遍增加，寒冷天数减少。在这里，我们提供了迄今为止对澳大利亚每日极端温度及其社会影响的最长的历史分析。我们使用新合并的早期仪器数据集和阿德莱德南澳大利亚州（该国最干旱的州，受澳大利亚热浪影响最大的城市）的一系列历史数据来调查日极端温度回升至1838年。我们确定了热浪和降雪事件发生频率的年代际变化，并在20世纪初达到顶峰，在1838-2019年期间，该地区的极端寒冷天气总体减少，热浪增加。文献和仪器记录表明，自二十世纪末以来，阿德莱德的降雪事件数量有所减少，热浪数量也明显增加。为了获得对南澳大利亚州历史极端现象的动态洞察力，我们提供了详细的案例研究，以比较历史性高温和寒冷极端的天气特征及其影响。我们特别强调1910年前期鲜为人知的事件和罕见的低海拔降雪。重要的是，这是第一项为减少澳大利亚低海拔降雪事件和寒冷爆发提供长期证据的研究。最后，