Leaf water potential is a good indicator of tree species responses to rainfall seasonality, allowing to better understand water stress effects on vegetation. We investigated daily and seasonal patterns on leaf water potentials of 21 dominant species in three distinct vegetation types from the Cerrado-Amazonia transition to assess how they respond to seasonal changes in water availability. We found that the variation on leaf water potential (Ψl) across species was higher in the dry compared to the rainy season, for all vegetation types. Typical cerrado and cerradão species showed similar patterns, with higher Ψl regulation under higher VPD and lower variation in predawn Ψl (ΔΨpd), indicating root access to soil water even during intense drought. In contrast, seasonal forest species showed lower regulation under lower VPD effects in both seasons, and higher ΔΨpd, indicating lower access to deep water in the soil. These differences revealed two main groups of species: higher Ψl regulators with a strategy isohydric occurring in both typical cerrado (savannah) and cerradão (woodland), and lower Ψl regulators with anisohydric strategy, occurring in seasonal forest. Our results suggest that seasonal tropical forest species will become very vulnerable to predicted increases on drought severity in the region.