This study examines the spatiotemporal changes in snow regimes across High Mountain Asia (HMA), with a focus on snowfall, snowmelt and snow water equivalent (SWE) trends and their relationship with elevation, temperature, and precipitation. Utilizing ERA5-Land data, the analysis reveals a general decrease in snowfall and SWE, as well as snowmelt in low to mid-elevations. Notably, high-elevation zones, despite also experiencing declining snowfall, exhibit increased snowmelt due to the persistence of deep snowpacks. However, the overall reduction in snowmelt across all basins, and significant decline of total snowmelt in the Brahmaputra, Indus, and other major river basins, underscores the critical impact of climate change on water resources. Correlation analyses further highlight complex interactions between temperature, precipitation, and snow regimes, varying by season and elevation. The study acknowledges limitations in ERA5-Land's accuracy, particularly in high-elevation regions, and calls for future research to incorporate multiple data sources and uncertainty analysis to improve the reliability of findings. The implications of declining snowmelt for water availability in major river basins are significant, warranting continued investigation.