Due to densely packed urban areas, urban heat islands and hot outdoor thermal environments have affected microclimatic conditions in Oman. These conditions have affected human thermal comfort and, thus, residents' lifestyles by discouraging walkability. Passive cooling strategies offer a sustainable approach to mitigate high temperatures and improve the thermal environment of public spaces such as alleyways. This study investigates various traditional passive cooling approaches' effectiveness in regulating thermal microclimate. It does so through fieldwork and numerical simulations, providing a comprehensive understanding of the factors that enhance outdoor thermal comfort in urban pathways in hot, arid environments like Oman. The fieldwork component involved measuring and analyzing the microclimate conditions, including air temperature, air velocity, and surface boundary radiation in urban open spaces, specifically alleyways, within a hot, arid city. The findings from this on-site data collection were then used to validate and calibrate a numerical model, which was subsequently employed to simulate the thermal performance of different cooling strategies. Using computational fluid dynamics (CFD) allowed for exploring a range of cooling interventions and their impact on outdoor thermal comfort, as measured by PMV. Adding water channels and adding acacia trees could induce an air temperature drop of up to 4.5°C and 7°C, respectively, establishing a cooling effect from evaporation. Increasing the aspect ratio from 0.5 to 2 reduced net radiation in the alleyway by 50%. A similar result was obtained by adding a set of palm trees, proving the shading potential of the narrow alleyways and palm trees in improving thermal conditions at the pedestrian level. Temperature reductions of up to 4°C occur in wide alleyways of aspect ratio 0.25 at low wind speeds. The results of this study have the potential to inform sustainable urban planning significantly and were used to develop design guidelines that emphasize the strategic placement of water bodies and vegetation. They demonstrate that a combination of passive cooling strategies, including strategically placing vegetation and water bodies and optimizing urban form, can significantly improve outdoor thermal comfort in hot, arid urban environments. Using numerical simulation, urban planners can identify the most effective cooling interventions, paving the way for a more sustainable city with enhanced walkability. Using the results from this thesis, two papers were generated, each accepted at a different conference. One paper, “The role of vegetation in outdoor thermal comfort of traditional alleyways in hot arid climates,” was presented at the Roomvent 2024 conference in Stockholm. Another paper, “Interaction of aspect ratio and water body on thermal microclimate in alleyways of Oman,” was presented at the PLEA 2024 conference in Poland.