This paper presents the periodicity of phenophases in 28 tree species (142 individuals), 58 shrub, and 72 herb species' populations for 23 months (during 2018-2020) vis-a-vis weather variability in four semi-deciduous and evergreen forests along an altitudinal transect (680-1860 m asl) in long-term ecological monitoring (LTEM) sites in Western Himalaya. Across these forests, atmospheric temperature, relative humidity, and annual rainfall declined significantly with increasing elevation. The autumn to winter period (October-February) of 2019 was characterized by higher temperature (0.49 °C), rainfall (48.5 mm), and relative humidity (9%) in comparison to 2018. Vegetative bud-break, leafing and leaf drop occurred predominantly in the spring season (March-April) followed by flowering and fruiting through summer until the onset of the rainy season. All the phenophases occurred in 3-4 episodes of varying magnitudes year-round, except for a few months during the rainy season. The year 2019 was characterized by earliness in bud-break and leafing by over 2 weeks as compared to 2018. This may be attributed to the greater elevation-dependant warming as reflected by the shallow mean annual temperature lapse rate (−0.36 ± 0.2 °C/100 m) observed for the study area than the commonly used value (−0.65 °C/100 m). In the warmer winter of 2019-20 owing to greater temperature and rainfall, the leaf senescence delayed resulting in a lower magnitude of leaf drop by ∼25% than that recorded in winter 2018-19. This shift may have certain structural and functional implications in these forests which need to be investigated for a longer period establishing LTEM sites to understand the impact of climate change.