Our study plans to quantify the effect of higher temperatures on different critical Turkish health outcomes mainly to chart future developments and to identify locations in Turkey that may be potential vulnerable hotspots. The general structure of the temperature mortality function was estimated with different fixed-level effects, with a specific focus on the mortality effect of maximum apparent temperature. Regional models were fitted to pinpoint the thresholds where the temperature–mortality relation changes, thus investigating whether the thresholds are determined nationally or regionally. The future patterns were estimated by extrapolating from future temperature trends: analyzing possible future mortality trends under the restricting assumption of minimal acclimation. Using the fixed effect regression structure, social and developmental variables acting as heat effect modifiers were also identified. In the largest dataset, the initial fixed effect regression specification supports the hypothesis summarized by the U-shaped relationship between temperature and mortality. This is a first corroboration for Turkish climate and health research. In addition, intermediation effects were substantiated for the level of urbanization and population density, and the human development and health development within provinces. Regional heterogeneity is substantiated by the mortality–temperature relationship and the significant threshold deviations from the national average.
