BACKGROUND AND AIM: The influence of elevated air temperatures recorded in various urban microenvironments in adversely impacting biologically relevant disease end points has not yet been extensively tackled. This {post hoc} analysis of the TEMP pilot trial, aimed to study the association between the 24-h personal air/skin temperature sensor measurements and the diary-based location type (indoors vs. outdoors) in various urban/rural microenvironments. METHODS: A total of 37 participants were included in the analysis. Wearable sensors were used for personal air/skin temperature, activity (as a surrogate marker of physical activity), while a time stamped personal diary recorded indoor or outdoor activities. Temperature peaks during a 24-h sampling period were detected using a peak finding algorithm. Mixed effect logistic regression models were fitted for the odds of participant location type as a function of setting and either personal temperature values or number of temperature peaks. RESULTS:Median [IQR] personal air temperature in indoor (micro)environments was lower than that in outdoors (28.0°C [26.4, 30.3] vs 28.5°C [26.8, 30.7], p 0.001), while median skin temperature [IQR] was higher indoors vs. outdoors (34.81°C [34.0, 35.6] and 33.9°C [32.9, 34.8]) (p0.001). The number of both personal air/skin temperature peaks was higher indoors compared to outdoors (median [IQR] 3.0 [2.0,4.0] vs 1.0 [1.0,1.3], p0.007, for the skin sensors). A significant association between the number of temperature peaks and indoor location types was observed with both sensor measurements (OR=3.1; 95% CI: 1.2-8.2; p=0.02 for air sensor and OR=3.7; 95% CI: 1.4-9.9; p=0.01 for skin sensor), suggesting higher number of indoor air temperature fluctuations. CONCLUSIONS:Amidst the global climate crisis, more population health studies or personalized medicine approaches that utilize continuous tracking of individual-level air/skin temperatures in both indoor/outdoor locations would be warranted, if we were to better characterize the disease phenotype in response to climate change manifestations. KEYWORDS: short-term exposure, climate, temperature extremes, temperature variability.