Spatial and Temporal Patterns of Thermal Discomfort in Romanian Moldavia: A Comparative Assessment Using the Temperature–Humidity Index (THI).

Thermal discomfort represents an essential component of the urban climate, resulting from the interaction between air temperature and relative humidity, with direct implications for public health and urban environmental quality. The present study aims to provide a comparative assessment of thermal discomfort in the main cities of Romanian Moldavia, using the Temperature–Humidity Index (THI) as a synthetic indicator of heat stress. The analysis is based on hourly meteorological data series recorded at automatic air quality monitoring stations located in the municipalities of Suceava, Botoșani, Iași, Piatra Neamț, Bacău, Vaslui, Focșani, and Galați, covering the period 2009–2025. The results reveal a non-uniform spatial and temporal distribution of thermal discomfort, determined by regional and local geographical factors such as relief, altitude, degree of continentality, and urban environmental characteristics. Cities in the Eastern part of the region, particularly Iași and Galați, record the highest THI values and the largest number of days with severe discomfort, reflecting increased exposure to continental warm air masses and the influence of extensive built-up surfaces. In contrast, sub-Carpathian cities such as Piatra Neamț and Suceava exhibit a more moderate regime due to higher altitude and the influence of relief on local air circulation. The analysis of the monthly and diurnal regimes indicates a pronounced concentration of thermal discomfort during the summer season, with peak values in July and August and within the time interval 12:00–18:00. Although no linear increasing trend in annual mean THI values is identified, interannual variability highlights the influence of extreme heat episodes on the urban environment. The findings emphasize the decisive role of geographical factors in controlling the distribution of thermal discomfort and demonstrate the existence of significant internal climatic differentiation within the analyzed region. This study contributes to a better understanding of the relationship between the urban environment and local climate and provides a scientific basis for the development of heat adaptation strategies in the cities of Moldavia.