<p>Glacier Surface Temperature (GST) is a key indicator of climatic change, but it is also intimately tied to glacier physical processes and mass balance. Over the last two decades, glaciers on the Third Pole have lost mass in a variety of ways but at an increased rate. This study investigates the long-term spatiotemporal variations of GST across the Durung Drung and Pensilungpa glaciers in the Zanskar region of the Western Himalaya from 1990 to 2020 using multi-temporal Landsat thermal infrared data. The retrieved GST patterns reveal a distinct altitudinal gradient, with surface temperature decreasing with increasing elevation at an average lapse rate ranging between − 0.0011&#xa0;°C m^− 1 and − 0.0023&#xa0;°C m^− 1. The lowest GST values occur in the accumulation zones, while higher temperatures dominate the debris-covered ablation areas, highlighting the strong influence of local topography, surface characteristics, and debris thickness on thermal heterogeneity. Temporal analysis indicates persistent elevation-dependent temperature gradients, with noticeable variations in lapse-rate magnitude in recent decades. Furthermore, expansion of supraglacial debris cover has altered surface melt intensity and spatial variability, with debris-covered zones showing complex melt responses. The findings demonstrate the utility of long-term satellite-derived thermal datasets for monitoring GST evolution and provide critical insights into the climatic and geomorphic controls on glacier melting in the high-altitude Himalayan environment.</p>