Abstract We analyze changes in the maximum annual transient snowline elevation (MATSL) of glaciers for two regions in western North America from 1984 to 2024 using five satellite remote sensing datasets. MATSL reached its highest elevations in 2019 (155 m above the long-term average) for Alaska (Region 1) and in 2023 (148 m) for Western Canada and USA (Region 2). The rate of MATSL rise accelerated fourfold, increasing from 2.1 ± 0.8 m a−1 in 1984–2010 (r 2 = 0.1, p < 0.01) to 8.9 ± 1.7 m a−1 in 2010–2024 (r 2 = 0.5, p < 0.01). In 2019, 91 glaciers exceeded the 95th percentile MATSL elevation, a threshold indicative of complete loss of the accumulation area, in Region 1. In Region 2, 149 glaciers exceeded this threshold in 2023. Year-to-year variability in MATSL was strongly influenced by mean summer air temperature with sensitivities of +46 m °C−1 (r 2 = 0.54) and +23 m °C−1 (r 2 = 0.30) for Regions 1 and 2, respectively. Mean spring snow water equivalent also played an important role with sensitivities of −351 mm w.e.−1 (r 2 = 0.48) and −155 mm w.e.−1 (r 2 = 0.37), respectively. Per-glacier analysis revealed that south-facing slopes experienced the largest MATSL increases. Terrain attributes, including slope, aspect, hypsometry, and elevation, enhanced MATSL prediction models compared to those using only climate variables. The pronounced rise in MATSL underscores a critical glacier melt feedback mechanism, warranting further investigation. This study highlights the utility of automated MATSL time-series mapping for regional-scale analyses and identifies key limitations and opportunities for future research.