Mapping summer microclimates
We partnered with the Urban Transformations Research Centre at Western Sydney University to document air temperature and relative humidity variations across the local area.
In summer, millions visit Sydney’s famous sites, enjoy festivals, aquatic recreation and dine outdoors. But summers are getting hotter, with air temperatures exceeding 40°C more often in parts of the city.
This presents significant health risks for residents, workers and visitors. So we set out to find the critical hotspots and cool places and learn how much air temperature varies across the local area during extreme heat events.
Understanding Sydney’s heat patterns
This study provides critical empirical data to help the City of Sydney adapt to hotter summers.
From December 2023 to March 2024, researchers collected more than 1.5 million measurements from 127 locations. The data was used to produce the most detailed analysis of the area’s summer microclimates to date.
Key findings
- Temperature variability: Air temperatures differ significantly across the city. During hot (35°C+) and extreme heat (40°C+) days, temperature differences from north to south can exceed 10°C.
- Hottest areas: Southern suburbs like Alexandria, Rosebery and Beaconsfield experience the highest daytime temperatures.
- Cooler areas: Central Sydney and harbourside suburbs remain relatively cooler during the day but retain the most heat at night due to materials such as concrete absorbing, storing and releasing heat.
- Notable hotspots: The highest mean summer temperature (24.7°C) was recorded in Pyrmont, Camperdown, Woolloomooloo and Surry Hills. The hottest recorded air temperature was 45.3°C in Church Street, St Peters, at 12:40pm on 9 December 2023. At the same time, and only 6.4km away, air temperature in the Royal Botanic Garden was 30.0°C.
- Coolest locations: The Royal Botanic Garden, Centennial Park and Moore Park recorded significantly lower temperatures, demonstrating the cooling impact of green spaces.
- Urban heat islands: Areas with limited tree canopy, high-density development and extensive hard surfaces showed elevated temperatures, reinforcing the importance of urban greenery.
- Unexpected cool zone: Despite its industrial surroundings and limited shade, Joynton Avenue in Zetland recorded among the lowest temperatures. This could be attributed to the high tree canopy cover around the immediate measurement location, underscoring the role of vegetation in reducing heat.
This data was collected on 26 January 2024. Based on measurements of air temperature and relative humidity, unique microclimate maps in the research report visualise variation of the Universal Thermal Climate Index. This index reveals the substantial thermal differences across the area during hot days. In a world-first, microclimate maps and animations like this reveal the intensity and spatial extent of the Sydney Harbour breeze when cooling the city in summer.
Implications for climate resilience
The study reveals extreme heat is often underreported by official weather stations, increasing the risk of people vulnerable to heat being unprepared. To reduce heat-related problems, the study recommends the City of Sydney does the following:
- Create cooling projects city-wide particularly in central, southern and western suburbs.
- Increase effective cooling measures through direct actions such as more shade and indirect actions including regulatory changes.
- Reduce surface heat with more shade, reflective materials and by reducing hard surfaces.
- Set up a microclimate monitoring network to measure the long-term impact of cooling strategies.
- Identify and promote cool places such as parks, community centres, libraries and pools, especially before and during extreme heat events.
- Support community education programs to help residents and businesses prepare for extreme heat.
- Set measurable targets for success, with defined timelines for completion.
Looking ahead
Findings from this research will inform future climate resilience planning for Sydney. By making the most of detailed microclimate data, we can implement solutions to help protect people and enhance the city’s liveability in a warming climate.
