Infrared thermography is widely used for physiological monitoring and injury prevention in sports and health sciences. Two approaches are commonly employed in the literature for thermogram interpretation: contralateral comparison and the use of absolute temperature values. However, the interrelationships among different anatomical regions have not yet been systematically investigated. This study aims to establish inter-regional thermal relationships as a novel framework for defining normative thermal behavior. A retrospective analysis was conducted on the entire ThermoHuman® anonymized database, comprising over 25,000 upper-body and 100,000 lower-body thermograms, acquired under standardized imaging protocols (anterior/posterior, upper/lower views). For each thermogram, mean temperatures were extracted. Across nearly all anatomical regions, men consistently exhibited higher mean skin temperatures than women, with differences ranging from +0.09 ℃ to +1.64 ℃. A clear proximal-to-distal temperature gradient was observed in both sexes, with abrupt decreases between the forearm and wrist, as well as between the leg and ankle. To enhance interpretability, sex-specific normative thermal reference tables were developed, supported by gradient analysis to contextualize spatial thermal responses. These findings reinforce the clinical utility of IRT as an objective, reproducible tool for detecting physiological inter-regional patterns and guiding individualized assessments.