Tropical dry deciduous forests are among the most climate-sensitive ecosystems globally, yet their phenological responses to environmental change remain poorly documented, particularly in South Asia. This study addresses a critical knowledge gap by providing the first comprehensive phenological assessment of India's Gir Forest National Park, a globally significant tropical dry deciduous ecosystem, using high-temporal resolution PhenoCam technology. We deployed systematic near-surface remote sensing over 19 months (October 2022–May 2024), extracting green chromatic coordinates (GCC) from strategically defined regions of interest to quantify canopy-level phenological transitions with unprecedented precision. Our analysis revealed distinct asymmetric phenological patterns: an extended green-up period of 164 days contrasted with a rapid senescence phase of only 39 days. Median GCC values ranged from 0.332 to 0.368, demonstrating remarkable seasonal stability and providing robust phenological metrics for leaf emergence, peak greenness, and senescence timing. These findings establish critical baseline data for a previously unmonitored ecosystem and reveal phenological characteristics that may indicate adaptive responses to patterns in moisture availability in water-limited tropical environments. The pronounced asymmetry in green-up versus senescence periods suggests complex interactions between monsoon dynamics and vegetation physiology, with significant implications for carbon cycling, water balance, and ecosystem resilience under climate change scenarios. Our methodological framework offers a replicable, cost-effective approach for long-term phenological monitoring in data-sparse tropical regions. As climate change accelerates phenological shifts globally, this research provides essential reference data for predictive ecosystem modeling, biodiversity conservation planning, and climate adaptation strategies in tropical dry forests. The insights generated are particularly timely given the vulnerability of tropical deciduous ecosystems to altered precipitation regimes and projected temperature extremes in South Asia. This study advances our understanding of tropical forest phenology and establishes a foundation for examining climate-vegetation interactions in understudied ecosystems facing unprecedented environmental pressures.