Executive summary
Coastal New South Wales experienced damaging weather impacts in 2025 amid mixed and uncertain rainfall trends. World Weather Attribution analysis shows that while long-term changes in average rainfall remain unclear, heavy rainfall events are intensifying, increasing the risk of flooding and associated damage. The findings underline that uncertainty in rainfall trends does not imply low risk and that adaptation planning must account for more intense extremes alongside growing exposure in coastal communities.
What happened
In 2025, coastal regions of New South Wales experienced a combination of intense rainfall events and periods of relative dryness. Several heavy rainfall episodes led to river flooding, flash flooding and coastal inundation, affecting towns, transport corridors and agricultural areas.
Flood impacts were compounded by saturated catchments from earlier rainfall and by development in flood-prone coastal zones. Damage to homes, roads and essential infrastructure disrupted local economies and placed pressure on emergency services.
What the attribution analysis found
World Weather Attribution finds that the influence of climate change on average rainfall in coastal New South Wales is uncertain, with natural variability remaining a strong driver. However, the analysis shows clearer evidence that extreme rainfall events are becoming more intense as the climate warms.
Warmer atmospheric conditions increase the amount of moisture available during storms, leading to heavier downpours when rain occurs. This means that even without a strong trend in total rainfall, the risk of damaging floods is increasing.
The study highlights that planning based solely on changes in average rainfall misses the more critical signal in extremes.
Exposure, development and compounding risk
A key conclusion of the analysis is that growing exposure is amplifying impacts. Coastal population growth, expansion of housing and infrastructure into flood-prone areas, and ageing drainage systems have increased vulnerability to intense rainfall.
In many locations, existing flood mitigation measures were designed for historical rainfall intensities and are increasingly being exceeded during extreme events.
How climate attribution fits into rainfall and flood risk reporting
Climate attribution helps clarify how climate change is influencing different aspects of rainfall. In this case, attribution distinguishes between uncertain trends in averages and clearer increases in extremes, supporting a more nuanced approach to risk assessment.
For flood risk reporting, this reinforces the need to focus on peak rainfall and runoff rather than relying on long-term mean rainfall projections.
Why this matters for organisations
For local governments, insurers, utilities and businesses operating in coastal New South Wales, the findings highlight growing exposure to flood-related disruption and losses. Transport links, tourism assets and coastal infrastructure are particularly vulnerable to intense rainfall events that exceed design standards.
How to use this in your own risk work
Organisations should incorporate climate-adjusted extreme rainfall scenarios into flood risk assessments, review land-use planning and infrastructure capacity, and stress-test assets against higher peak rainfall events. Investing in resilient drainage, flood mitigation and early warning systems will be critical to managing risk under increasing rainfall intensity.
Source
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/