The completion of version 2 of the ACORN-SAT temperature dataset allows a new assessment of long-term changes in Australian temperature extremes. In general, changes in temperature extremes are consistent with observed warming in mean temperatures, but with some local variations.

There is no consistent pattern in Australia of extreme high temperatures warming faster than mean annual or summer maximum temperatures, in contrast to some northern hemisphere continents, particularly Europe. In much of northern and western Australia, and exposed east coast locations, extremes show less of a warming trend than means. In contrast, extremes are warming faster than mean summer maximum temperatures in much of the southeast quarter of Australia and at inland east coast locations, notably western suburbs of Sydney and Brisbane (in contrast to the coast itself). The weak post-1980 trends in winter minimum temperature in parts of inland southern Australia which have experienced significant cool-season drying since the 1970s are generally manifested similarly in means and extremes.

An assessment of the ratio between high and low temperature records has been extended over the full post-1910 period. Considering station records by month, high records have dominated low records in recent years. In the 2013-2018 period, this is by a ratio of about 10:1 for both maximum and minimum temperatures relative to the full 1910-2018 period, and 6:1 for 1960-2018. The ratio in 2013-2018 is even higher when only records broken by margins outside the range of measurement uncertainty are considered. Episodes of extreme heat affecting large areas show dramatic increases in frequency over the century, with the average frequency of days with the Australian area-averaged mean temperature above the 99^th percentile increasing from 0.6 per year in 1910-1949 to 14.0 per year in 2010-2018. This is an even stronger signal than that previously reported using the unhomogenised AWAP dataset.