Mixed rainfall trends highlight the importance of climate adaptation in coastal New South Wales

An attribution study of heavy rainfall in coastal New South Wales from May 19-22, 2025, found mixed results regarding the influence of climate change. While observational data suggests a doubling in likelihood for the wettest four-day annual event in a 1.3°C warmer climate, climate models show substantial disagreement on rainfall trends for the region. The study emphasizes the need for flexible adaptation strategies due to this uncertainty.

• The heavy rainfall event from May 19-22, 2025, which caused five deaths and isolated 50,000 people, is relatively common for the Coastal New South Wales Region, with an expected frequency of once every 10 years for the April-June season and once every 3 years when considering the full year.
• Observational comparisons indicate that in a climate 1.3°C warmer, the likelihood of the wettest four-day annual event approximately doubles, and its intensity increases by about 10%. Conversely, for the April-June season, a 1.3°C cooler climate would have seen a decrease in likelihood and intensity of about 17%.
• Climate model data for the region shows substantial disagreement, with some models projecting increases and others projecting decreases in heavy rainfall for both annual and seasonal periods, making it impossible to obtain a meaningful overarching result from the simulations.
• Analysis of atmospheric circulation patterns between 1950–1980 and 1994–2024 suggests a seasonal shift, where patterns leading to heavy rainfall are now more frequent in May and less common in March, though firm conclusions are difficult to draw.
• Due to the uncertainty and lack of a clear trend in rainfall projections, the study recommends flexible, 'low-regrets' adaptation measures such as water storage, diversification, nature-based solutions, and improved risk management.

APA

World Weather Attribution (2025). Mixed rainfall trends highlight the importance of climate adaptation in coastal New South Wales. https://www.worldweatherattribution.org/mixed-rainfall-trends-highlight-the-importance-of-climate-adaptation-in-coastal-new-south-wales/

Chicago

World Weather Attribution. Mixed rainfall trends highlight the importance of climate adaptation in coastal New South Wales. 2025. https://www.worldweatherattribution.org/mixed-rainfall-trends-highlight-the-importance-of-climate-adaptation-in-coastal-new-south-wales/.

Wikipedia

{{cite report |author=World Weather Attribution |title=Mixed rainfall trends highlight the importance of climate adaptation in coastal New South Wales |date=4 June 2025 |url=https://www.worldweatherattribution.org/mixed-rainfall-trends-highlight-the-importance-of-climate-adaptation-in-coastal-new-south-wales/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{worldweatherattribution2025mixed, author = {{World Weather Attribution}}, title = {{Mixed rainfall trends highlight the importance of climate adaptation in coastal New South Wales}}, institution = {World Weather Attribution}, year = {2025}, month = jun, url = {https://www.worldweatherattribution.org/mixed-rainfall-trends-highlight-the-importance-of-climate-adaptation-in-coastal-new-south-wales/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }