Understanding the key drivers controlling rainfall stable isotope variations in inland tropical regions remains a global challenge. We present novel high-frequency isotope data (5-30 minute intervals) to disentangle the evolution of six stratiform rainfall events (N=112) during the passage of convective systems in inland Brazil (September 2019-June 2020). These systems produced stratiform rainfall of variable cloud features. Depleted stratiform events (δ18Oinitial ≤ -4.2 ‰ and δ18Omean ≤ -6.1 ‰) were characterized by cooler cloud-top temperatures (≤-38 °C), larger areas (≥ 48 km2), higher liquid-ice ratios (≥ 3.1), and higher melting layer heights (≥3.8 km), compared to enriched stratiform events (δ18Oinitial ≥ -3.8 ‰ and δ18Omean ≥ -5.1 ‰). Cloud vertical structure variability was reflected in a wide range of δ18O temporal patterns and abrupt shifts in d-excess. Our findings provide a new perspective to the ongoing debate about isotopic variability and the partitioning of rainfall types across the tropics.