Climate change with increasing temperature is making a significant impact on human health,including more heat-related diseases,and increasing the burden on the healthcare system.Although many studies have explored the association between increasing temperatures and negative health outcomes,research on the associated costs of heat-related diseases remains relatively sparse.Furthermore,estimations of future costs associated with heat-attributable hospital healthcare have not been well explored.This study used a distributed lag nonlinear model to estimate heat-attributable hospital healthcare costs in Perth,Western Australia.Using 2006-2012 as the baseline,future costings for 2026-2032 and 2046-2052 were estimated under RCP2.6,RCP4.5,and RCP8.5.Higher temperatures were found to be associated with increased hospital healthcare costs.The total hospital costs attributable to heat over the baseline period 2006-2012 was estimated to be 79.5 million AUD,with costs for mental health hospitalizations being the largest contributor of the heat-related conditions examined.Costs are estimated to increase substantially to 125.8-129.1 million AUD in 2026-2032,and 174.1-190.3 million AUD by midcentury under climate change scenarios.Our findings of a notable burden of heat-attributable healthcare costs now and in the future emphasize the importance of climate change adaptation measures to reduce the adverse health effects of increasing temperatures and heat exposure on the people of Perth.