Days 35 degrees and above

Key Messages

• Days 35°C and above will become more frequent under all 3 emissions scenarios in NSW.
• By the end of the century, Sydney could experience more than triple the number of hot days per year under a high-emissions scenario.
• The Far West, New England and North West, and Central West and Orana regions are projected to experience the greatest increases in the number of Hot Days. However, coastal regions of NSW will experience see a large increase in the number of hot days under all emissions scenarios.
• NARCliM 2.0 provides high-resolution climate change projections for NSW and south-east Australia. 

Context

What factors influence extreme heat?

Hot days – days 35°C and above – are a common occurrence in parts of Australia, however the ongoing impacts of hot days on communities and the environment can be extreme.

As our climate changes, so too does the influence and impact of hot days. Prolonged hot days where maximum temperatures are 35°C and above increase the incidence of illness and death, particularly among vulnerable people.

When do days 35°C and above occur? 

Days 35°C and above are most common across NSW during summer months however can still occur during spring and autumn. Hot days rarely occur outside of spring and summer months, however climate change may increase their occurrence in early autumn and late spring. 

Where can hot days occur?

The climate of NSW is variable however days 35°C and above can occur in most regions of the state. ‘Average’ summer temperatures vary from location to location and what is a common occurrence in one part of the state, such as Western NSW, can be uncommon in others, such as alpine region. 

Impacts

All sections of the community are impacted by extreme heat. These range from natural environment and its impacts on plants¹, animals and water², agriculture³ (crop vulnerability to heat damage), the built environment and heat island affect⁴, transportation and its impacts on infrastructure and safety, and health⁵ (increased periods of elevated heat stress). 

Key findings

35°C and above

New South Wales (NSW) and Australian Regional Climate Modelling (NARCliM) data provides information on the number of days where maximum temperature is greater than or equal to 35°C (TXge35). For regional information see the NSW climate change snapshots.

Climate projections

NARCliM2.0 projections show that across NSW, the average number of hot days per year will increase throughout this century under a low- (SSP1-2.6) medium- (SSP2-4.5) and high-emissions (SSP3-7.0) scenario (Figure 1). 

During the baseline periodⁱ,1990–2009, NSW had on average 37.9 hot days annually. 

By the middle of the centuryⁱⁱ:

The average number of hot days is projected to increase by: 

• 14. 8 per year under a low-emissions (SSP1-2.6) scenario
• 18.3 per year under a medium-emissions (SSP2-4.5) scenario
• 23.1 hot days per year under a high-emissions (SSP3-7.0) scenario

By the end of the centuryⁱⁱⁱ:

The average number of hot days is projected to increase by: 

• 15.9 per year under a low-emissions (SSP1-2.6) scenario
• 31.7 per year under a medium-emissions (SSP2-4.5) scenario
• 45.5 per year under a high-emissions (SSP3-7.0) scenario.

The regions of Far West, New England and North West and Central West and Orana are projected to experience an additional 15–30 hot days per year under a low-emissions scenario, 25–50 additional hot days under a medium-emissions scenario and 40–60 additional hot days per year under a high-emissions scenario.

The number of hot days for coastal regions is projected to increase on average by an additional 5–10 days per year under a low-emissions scenario (SSP1-2.6) and by an additional 15–25 days per year under a high-emissions (SSP3-7.0) scenario.

Geographic impacts - days 35°C and above

While days 35°C and above are regular occurrences in select parts of NSW, increases in the number of hot days are expected for all regions across the state under all 3 emissions scenarios. This will particularly be seen in the Far West, New England and North West, and Central West and Orana regions (Figure 1 and 2).

Due to the cooling influence of the ocean, coastal regions of NSW will experience fewer hot days compared to warmer inland regions, but these regions will still see a large increase in the number of hot days under all emissions scenarios.

Application and adaptation

By understanding future projections, we can better understand and plan for a changing future and the future impacts of increasing extreme heat.

Implications of days 35°C and above

Increased hot days can lead to other extreme heat events – such as heatwaves – which can have significant impacts on public health, agriculture and infrastructure.  

For example, instances of heat stress from days 35°C and above impact the health sector which may be required to deal with more frequent heat-related illness.⁶ Crops and livestock can be impacted from heat stress due to hot days, which may impact the industry.⁷ 

Furthermore, increased frequency of days 35°C and above places more stress on infrastructure that may have been designed for historical temperatures and heatwave frequency and may increase. Adaptation strategies such as urban planning and building design with future climate projections will assist in designing future communities to withstand the future climate conditions to which communities, infrastructure and buildings could be exposed to.

References

1. NSW Government, Natural Environment: Climate change impacts on the NSW natural environment, Accessed 20/11/25
2. NSW Government, Natural Environment: Climate change impacts on the NSW natural environment, Accessed 20/11/25
3. NSW Government, Agriculture: Climate change impacts on our agriculture, Accessed 20/11/25
4. NSW Government, Built environment: Urban Heat, Accessed 20/11/25
5. NSW Government, Impacts of climate change: Climate change impacts on our health and wellbeing, Accessed 20/11/25
6. World Health Organization, ‘Heat and health’, WHO website, 2024, accessed 14 November 2025,
7. Climate Council, Global warming impacts on food and farming in Australia, Climate Council, 2014, accessed 14 November 2025.

Technical information

NARCliM data provides information on the number of days where maximum temperature is greater than or equal to 35°C (TXge35). The use of NARCliM2.0 maximum temperature is greater than or equal to 35°C (TXge35) data provides insights into what the next 75 years may show. 

Time periods in this document

i. Baseline period: The modelled average for each climate variable from 1990–2009, used for comparison with future projections.

ii. Middle of the century: The projected annual average for days 35°C for 2040 to 2059. This is compared against a historical model baseline period of 1990 to 2009 (37.9 Hot days). The projections for each time period represent averaged data across all 10 NARCliM climate models.

iii. End of the century: The projected average for days 35°C for 2080-2099. This is compared against a historical model baseline period of 1990 to 2009 (37.9 Hot days). The projections for each time period represent averaged data across all 10 NARCliM climate models.

Further reading and information

NARCliM2.0

New South Wales and Australian Regional Climate Modelling (NARCliM)2.0 provides nation-leading climate model data that spans the range of plausible future changes in climate. It offers:  

• climate projections to the year 2100, and simulations of the past  
• 4-km scale projections for south-east Australia, 20-km scale projections for the broader Australasian region
• projections under low (SSP1–2.6), medium (SSP2–4.5), and high (SSP3–7.0) emissions scenarios to understand how climate risk differs depending on emissions pathways (Shared Socioeconomic Pathways, SSPs). 
   

NARCliM2.0 Resources (Adapt NSW)

Regional Climate Change Snapshots: The NARCliM2.0 projections are summarised as snapshots to provide accessible climate information that can support NSW communities to understand and plan for the impacts of climate change

Interactive Climate Change Projections Map: Select the region, climate variables and timescale in your area to explore what your region may look like in the future.

Climate Data Portal: The NSW Climate Data Portal variables dictionary provides technical descriptions and applications for each index 

NSW Government, The NARCliM modelling methodology, Adapt NSW