This study focuses on assessing tourists' perception of bioclimatic comfort in the urban context of Porto, Portugal, specifically in the areas of Avenida dos Aliados and Praça da Liberdade. The study examines the relationship between meteorological conditions, tourists' clothing choices, and their physical activity levels. The study integrates microclimatic measurements and questionnaire surveys carried out during the summers of 2019 and 2020, and the winter of 2019-2020. A comprehensive questionnaire following international standards was administered to a representative sample of 563 tourists. The results show significant variations in mean air temperature (AT), wind speed (Wχ), relative humidity (RH), global radiation (GRAD), and total mean radiant temperature (TMRT) over the study periods. The assessment of Outdoor Thermal Comfort (OTC) is based on ASHRAE 55 standards, using the Thermal Sensation Vote (TSV) scale and the tourists' opinions on their thermal preferences. Clothing choices are found to be influenced by AT, with tourists choosing lighter clothing in warmer conditions. Gender and age differences in clothing insulation (Icl) are identified, suggesting potential differences in OTC perception. AT varied significantly, with an inflection point in clothing choices at 21.7°C and a correlation between AT and reduction in clothing layers (r2 = 0.846; p < 0.05). The study also observes seasonal variations in physical activity levels of tourists, with higher activity levels in summer due to milder weather (110.0 W·m⁻2). More thermally comfortable environments tend to promote a sense of well-being among visitors, which directly affects their satisfaction during their stay in the city. When tourists feel comfortable with the thermal conditions of the urban environment, they are more likely to explore and enjoy local attractions for longer periods of time, thereby enhancing their cultural and leisure experiences. Women tend to wear fewer layers of clothing than men in summer, reflecting potential differences in OTC perception. Results align with previous studies, indicating the impact of clothing insulation of individual subject (Icl) on OTC varies across locations and cultures. Cultural factors influence clothing preferences and thermal tolerance, emphasizing the need for nuanced considerations in understanding OTC perceptions. The study provides to the understanding of the OTC of tourists in the city of Porto, but also offers relevant contributions for improving the visitor experience and sustainable development, namely in other geographical contexts. The major contribution of this research lies in the comparative analysis of Icl and OTC between tourists, based on physical measurements and questionnaire surveys conducted in summer and winter, providing valuable insights for tourist spot design.
