High-elevation regions with complex orography pose major challenges for estimating local precipitation and snow-related variables due to sparse observations and strong spatial variability. To bridge this gap, the Modèle Atmosphérique Régional (MAR) has been used to generate a high-resolution, century-long atmospheric reanalysis over High Mountain Asia spanning 1900 to the present. The model has been calibrated using both local meteorological observations and remote sensing, and is driven by global reanalyses, including ERA5 (1950–present) and ERA-20C (1900–2010) to achieve a comprehensive coverage of the 20th century. This centennial atmospheric reanalysis provides unprecedented insights into interannual variability, long-term trends, and the links between large-scale atmospheric circulation and local climatic conditions, including elevation contrasts. Its fine spatial resolution significantly serves to improve our understanding of cryosphere-climate interactions and supports a wide range of applications in High Mountain Asia.