Abstract The onset timing of the flash drought season (TO) critically determines whether these rapid‐intensifying events coincide with sensitive stages of vegetation growth, as droughts occurring early in the growing season can severely undermine ecosystem productivity. However, how TO has evolved under climate change remains unclear. To address this gap, we analyze TO trends across global vegetated areas from 1982 to 2023 and reveal a widespread but regionally heterogeneous advance, averaging approximately one day earlier per decade. This shift is particularly pronounced in northern mid‐ to high‐latitudes and in forested regions. Spatial and temporal attribution analyses further demonstrate that, conditioned on region‐specific baseline climatic conditions, significant TO trends are strongly associated with spring greening and warming in more than 56.4% of the examined regions. The observed advance implies an increasing temporal overlap between drought and critical vegetation growth phases, which may pose emerging challenges for ecosystems and climate adaptation.