The goal is to increase the contribution that the urban tree canopy and water in the landscape can make to the quality of public places, streets and open spaces which improves amenity.
- Number of hot days (at or above 35ºC) (updated)
- Urban heat impacts (new)
- Proportion of permeable surface cover (new)
- Investment in tree planting (new)
Hot days and heatwaves are a significant hazard in Greater Sydney, impacting people’s health and local amenity. Green infrastructure such as tree canopy can mitigate this by reflecting radiant heat, providing shade and cooling the microclimate through transpiration. Programs to increase urban tree canopy cover include the NSW Government’s 5 Million Trees Program and council-led tree planting programs39.
Our evidence base has expanded to include insights on permeable surfaces, recognising how retaining more water in the landscape can also help mitigate the urban heat island effect.
Further research also highlighted how Sydney Water’s investments in reinstating more natural conditions in highly modified waterways not only helps retain more water in the landscape but can also support increased tree canopy cover and a range of liveability and sustainability objectives.
Hot days and heatwaves
In 2019-20 the number of hot days (at or above 35 degrees Celsius) was above the long-term average across all districts (Figure 20). For example, Penrith (in Western City District) recorded 35 hot days, well above the long-term average of 22.7 days. Similarly, Parramatta (in Central City District) recorded 16 hot days (the long-term average is 11.3 days). In the Eastern City District, nine hot days were recorded at Observatory Hill (3.2 average). During the summer of 2019-20, there were fewer hot days in the Western City, Central City and South districts than the previous year (2018-19), and more hot days in the Eastern City and North districts (see Figure 21).
Heatwaves occur when temperatures remain high for that location for three or more consecutive days40. For example, there were six consecutive days over 35 degrees in Penrith from 26 to 31 December 2019, with a peak temperature of 46.3 degrees on 31 December 2019. By contrast, Observatory Hill in the Eastern City District did not record any heatwaves in 2019-20.
Figure 20: Number of days at or over 35°C (July 2009-June 2020)41