Observed and projected increases in short-duration extreme precipitation under climate change over Greater Sydney

Abstract Emerging observational evidence shows an intensification of short-duration precipitation events (⩽1 h) at a faster rate than longer-duration events, these short-duration extreme precipitation events frequently trigger flash floods and pose significant risks in urban areas to infrastructure and people. Despite this, regional-scale assessments of sub-hourly to hourly precipitation events remain scarce. Using 16 automated weather stations, we analyze short-duration extreme precipitation (5-, 10-, 20-, 30-, and 60 min) events across the rapidly urbanizing Greater Sydney region, New South Wales, Australia. Our analysis reveals strong increasing trend in extreme precipitation (99th (p99) and 99.5th percentiles (p99.5)) at 5–10 min compared to hourly scale. At the hourly scale, an ensemble of ten convection-permitting regional climate model simulations (4 km resolution) reproduces the upper tail of the precipitation distribution but slightly overestimate the frequency of extreme events. Future projections under three Shared Socioeconomic Pathway (SSP) scenarios (SSP126, SSP245, SSP370) show a consistent intensification of p99 precipitation, with the largest increases under SSP370 and a pronounced shift in the upper 1% of historical extremes (up to 125%). In contrast, the total number of wet hours decreases, indicating a transition toward shorter and more intense precipitation events. Despite inter-model spread and spatial variability, models project an increase in median trend at p99 extremes across most scenarios (up to 0.15 mm yr −1 ). Under the low-emission scenario (SSP126), a reduction in extreme precipitation is projected in the far future, highlighting the potential benefits of mitigation. These findings highlight the need to integrate short duration extreme precipitation events into urban planning and to mitigate escalating flood risks under climate change.