The new climatic normals and their impact on bioclimatic indices. Case study: Oradea (Romania)

This study examines the impact of new climatic normals (1991–2020 vs. 1961–1990) on bioclimatic indices in Oradea, Romania, highlighting the dynamic relationship between climatic variability and bioclimatic stress. The research focuses on three key indices: Effective-Equivalent Temperature (EET), Temperature-Humidity Index (THI), and Wind Chill Index (WCI), selected for their relevance in reflecting bioclimatic discomfort and risk. The results reveal a gradual increase in air temperatures (+0.91°C annually), with more pronounced warming during summer (+1.33°C to +1.64°C) and winter (+2.29°C in January). These changes influence bioclimatic perceptions, with THI-min values shifting from "cold" to "cool" in summer months and THI-max in August evolving from "warm" to "very warm." The study identifies significant trends: the frequency of extreme maximum bioclimatic values has increased, while extreme minimum values have decreased, reflecting intensified heat stress. While WCI and WCET show relative stability due to wind's moderating effect, their influence diminishes, leading to increased thermal stress. Future projections suggest that bioclimatic trends will continue to rise, with THI values potentially aligning with mean air temperatures by 2118, indicating a stronger bioclimatic impact of warming. This research emphasises the necessity of addressing these changes in regional planning and public health strategies. It also highlights the broader implications for other Romanian regions, where temperature increases are more significant, and stresses the importance of further studies to assess bioclimatic impacts nationwide.