Heat stress in predominantly arid and semi-arid countries, such as Somalia, presents a significant environmental challenge, exacerbated by global warming and climate variability. This study comprehensively analyzes the changing patterns of heat stress in Somalia, utilizing the Wet Bulb Globe Temperature (WBGT) derived from hourly ERA5 reanalysis data from 1960 to 2023. The study employed a novel approach to assess spatiotemporal variations and changes in the frequency, intensity, and duration of heat stress across the country. The results reveal a statistically significant increase in heat stress conditions, particularly pronounced in the coastal and southern regions. A comparative analysis between the early period (1960-1991) and the later period (1992-2023) demonstrates substantial shifts in heat stress dynamics. Specifically, extreme heat stress events in coastal areas increased by 20%, from 13.5 to 16.2 occurrences annually, while severe heat stress events rose by 20.7%, from 28.5 in the early period to 34.2 in the late period, predominantly in northern coastal regions. High-intensity heat waves also showed a 20% increase, rising from 54.0 to 64.8 annual events in southern coastal areas. Notably, moderate heat stress events experienced the most dramatic surge, increasing by 20% from 87.0 to 104.4 occurrences annually, particularly in southern coastal regions. The duration of the extreme heat waves increased by 7.7%, 2.5%, 6.5%, and 3.4%, respectively, for high, severe, moderate, and extreme heat stress in the northern and southern coastal regions. The results indicate a clear warming trend characterized by a shift from lower to higher heat stress categories and a significant reduction in "no heat stress" hours across Somalia. The study underscores the urgent need for targeted adaptation strategies, improved heat-health action plans, and enhanced early warning systems to address the escalating risks of increasing heat stress in Somalia.Graphical AbstractThis graphical abstract visually summarizes the study on rising heat stress in Somalia over the past 60 years, using the Wet Bulb Globe Temperature (WBGT) index derived from hourly ERA5 reanalysis data (1960-2023). It illustrates the core components of WBGT-air temperature, humidity, solar radiation, and wind speed-and explains how these variables collectively influence human heat stress. The visual features a conceptual diagram highlighting the physiological response of the human body to WBGT conditions, emphasizing the shift from "no heat stress" to "extreme heat stress." This is complemented by a simplified schematic showing how WBGT is calculated, reinforcing the scientific foundation of the analysis. Key findings are presented through bar charts comparing two distinct periods: 1960-1991 and 1992-2023. The charts show a consistent increase in the frequency of extreme, severe, high, and moderate heat stress events, especially in coastal and southern regions. For instance, extreme heat stress events rose by 20%, and moderate events increased by over 20% in annual occurrences. The duration of long-lasting heat waves also increased across all intensity categories. A prominent upward trend graphic symbolizes the progression toward higher heat stress categories, while a heat map in the background subtly reflects regional vulnerability. The design employs a clean, professional color scheme to ensure clarity and accessibility, making the scientific content easily digestible.