Key points
- A heatwave is when maximum and minimum temperatures stay unusually high for 3 or more days.
- Heatwaves affect human health – they kill more Australians than any other natural hazard.
- Heatwaves also put pressure on our infrastructure and services and affect our environment and agriculture.
- Temperatures in NSW are increasing because of climate change. Climate change will also mean that we have more heatwaves, and they will be hotter and longer than they are now.
- Changes to our built environment, housing designs and agriculture will help to reduce the impact of projected heatwaves on our community and economy.
The impact of heatwaves in NSW
Heatwaves are a significant hazard in Australia.
They have been responsible for more human deaths than any other natural hazard, including bushfires, storms, tropical cyclones and floods. Tragically, during the 1939 Black Friday bushfires, 71 people died in Victoria. During the heatwaves leading up to those fires, at least 420 people died, mostly in NSW. Similarly, during the 2009 Victorian bushfires, 173 people died with an additional 374 deaths in the heatwave before the fires.
Heatwaves have the greatest impact on our most vulnerable populations – children, elderly people, Indigenous communities and people with pre-existing diseases and disabilities.
Heatwaves can increase the pressure on our health and emergency services. During heatwaves in 2011 and 2019, hospitals across NSW experienced a 14% rise in admissions.
Heatwaves also increase pressure on our water and energy supplies, causing water restrictions and blackouts. Power shortages can increase the health impact of heatwaves, because people can’t use air conditioning or other electrical methods to cool off.
Heatwave effects are often worse in cities, because hard surfaces such as bitumen can retain heat and drive up temperatures (known as the ‘heat island effect’).
Heatwaves also affect our agriculture and wildlife and can increase the risk of bushfires.
How heatwaves are affected by climate change in NSW
As a result of climate change, heatwaves in NSW are projected to be more intense, occur more often and last longer. We are already seeing these changes, and they are projected to continue in the future.
The intensity of heatwaves is measured in 2 common ways – the hottest day of the hottest heatwave of the year, and the average temperature across all heatwaves of the year.
The hottest day of the hottest heatwave is projected to increase across the state in both the near and far futures.
While the average temperature across all heatwaves is not projected to increase, the number of days of extreme heat (defined as days with temperatures above 40°C) each year is projected to significantly increase.
The number of heatwave events each year is projected to increase significantly for most of NSW and the ACT in the near future, with even more significant increases projected for the far future.
By 2070, the number of heatwaves is projected to increase from 2 events per year to 4.5–6.5 events per year, with the greatest increases in central and northern parts of NSW.
Heatwave duration is measured by the length of the longest heatwave of the year.
Heatwaves are projected to last longer in the future. By 2030, models suggest that the longest heatwave of the year will last 1.5-3.5 more days on average in most regions. By 2070, models suggest that the longest heatwave of the year will 2–11 more heatwave days per year on average, with the northern inland areas experiencing more than the south.
Adapting to heatwaves in NSW
The NSW Government is taking action on climate change through multiple pathways, including the Climate Change (Net Zero Future) Act 2023, the NSW Climate Change Adaptation Strategy and the NSW Climate Change Adaptation Action Plan 2025–2029.
Adapting our built environments and homes is an important way to minimise the impacts of increasing heatwaves. For example, designing our cities to reduce how much heat is absorbed by buildings and roads can reduce the ‘heat island effect’ and help to keep temperatures down. Designing our homes to keep cool in summer without using energy can improve our lives and reduce pressure on our energy supply.
We are also investigating how to adapt our farming practices to better suit increased temperatures and other effects of climate change. Adaptation strategies might include using different crops in different areas, different irrigation methods and new ways to manage livestock.
To help urban managers consider climate change in their planning, adaptation guidance is available on the climate-adapted urban green space management page and Climate change, green cover and open spaces page.
Related information
- Climate change and heatwaves – World Meteorological Organization
- Heatwave knowledge centre – Australian Bureau of MeteorologyAustralian Bureau of Meteorology
- Heat resilience program – Western Sydney Regional Organisation of Councils
- Greater heat resilience for Greater Sydney – AdaptNSW
- How can nature help tackle the urban heat island effect? – Greening Australia
Case studies
NSW councils are building climate risk into their business-as-usual planning and policies for the first time, thanks to products developed using NARCliM’s locally relevant climate modelled data.
Ensuring there’s enough water in the moat may not be a common challenge for those preparing for changing climate conditions.
Climate change creates a significant risk to infrastructure, people, and the economy. The impacts from climate change, including damaging weather events, has already cost the state an estimated $3.6 billion per year.