Abstract Extreme sub‐daily precipitation can lead to significant impacts, predominately through flash‐flooding. As the climate warms it is expected that the increased water‐holding capacity of the atmosphere—∼7% per C via the Clausius‐Clapeyron (CC) scaling relationship—will contribute to increases in the intensity of severe rainfall events, particularly at short time scales. In this study, trends in annual and seasonal maxima of sub‐daily precipitation accumulations from 1 to 24 hr are evaluated over regions of Australia within a quality controlled sub‐daily precipitation gauge data set. Station‐based trends are shown to be sensitive to choice of start and end year, but trends over periods longer than ∼25 years are less susceptible to internal variability and appear to be more stable. Hourly annual maximum rainfall trends are increasing for most periods over Australia and many of its regions, but as accumulations increase toward daily time scales the trends become smaller or negative. Seasonally, the largest increasing national‐average trends at hourly duration are found in the austral summer (DJF), a season that is more prone to thunderstorms than other times of year. In contrast, the austral autumn (MAM) has seen strongly decreasing trends at all durations, which aligns with the reduced mean rainfall seen over eastern areas of the continent.
Rafter et al. (Fri,) studied this question.