Background: Climate change projections have highlighted the need for public health planning for extremeheat. In Adelaide, South Australia, hot weather is characteristic of summer and heatwaves can have a significanthealth burden. This study examines the heat thresholds and temperature relationships for mortalityand morbidity outcomes in Adelaide.Methods: Daily maximum and minimum temperatures, daily mortality, ambulance call-outs, emergency department(ED) presentations and hospital admissions were obtained for Adelaide, between 1993 and 2009.Heat thresholds for health outcomes were estimated using an observed/expected analysis. Generalized estimatingequations were used to estimate the percentage increase in mortality and morbidity outcomes abovethe threshold temperatures, with adjustment for the effects of ozone (O3) and particulate matterb10 'm inmass median aerodynamic diameter (PM10). Effect estimates are reported as incidence rate ratios (IRRs).Results: Heat-related mortality and morbidity become apparent above maximum and minimum temperaturethresholds of 30 °C and 16 °C for mortality; 26 °C and 18 °C for ambulance call-outs; and 34 °C and 22 °C forheat-related ED presentations.Most health outcomes showed a positive relationship with daily temperaturesover thresholds. When adjusted for air pollutants, a 10 °C increase in maximum temperature was associatedwith a 4.9% increase in daily ambulance call-outs (IRR 1.049; 95% CI 1.027'1.072), and a 3.4% increase inmental health related hospital admissions (IRR 1.034; 95% CI 1.009'1.059) for the all-age population. HeatrelatedED presentations increased over 6-fold per 10 °C increase in maximum temperature. Daily temperatureswere also associated with all-cause and mental health related ED presentations. Associations betweentemperature over thresholds and daily mortality and renal hospital admissions were not significant when adjustedfor ozone and PM10; however at extreme temperatures mortality increased significantly with increasingheat duration.Conclusions: Heat-attributable mortality and morbidity are associated with elevated summer temperatures inAdelaide, particularly ambulance call-outs, mental health and heat-related illness.