Thermally uncomfortable outdoor environments can significantly affect liveability of cities. Australia is likely to experience between 0.6 °C and 3.8 °C increase in temperature by the end of the 21st century. In warmer climates, increased demand for indoor air-conditioning results in higher energy demand and greater waste heat production. Anthropogenic heat production in the built environment creates a feedback loop with outdoor heat stress and causes outdoor living decline in cities. Spatial heat resilience (SHR) is defined as the capability of the built environment to support outdoor activities during heat stress conditions. Public life observation surveys were conducted in Sydney, Melbourne and Adelaide between 2013 and 2015. Outdoor thermal neutrality and heat adaptation thresholds are determined and an indexing system to indicate spatial heat resilience is presented. Correlations between SHR and urban surface covers are discussed further. Results highlight that outdoor activities decrease systematically after the neutral thermal threshold of 28-32°C. Outdoor heat adaptation can be extended by the critical thermal threshold of 42°C. Tree canopy, natural landscapes, supportive land use and public space management can extend heat resilience in public space. Particularly, increased tree canopies up to 30% correlates to increased heat stress resilience. Heat resilient public spaces can support more liveable public spaces in the context of climate change.