Atmospheric and cloud microphysical drivers of extreme precipitation over a coastal region: the Mumbai 2025 event

Human-induced atmospheric warming has increased the frequency and intensity of extreme precipitation events by enhancing atmospheric moisture availability. The geographical location of India makes it particularly susceptible to stronger and often extreme rainfall episodes. After 13 years, Mumbai recorded its third-highest single-day rainfall on 16 August 2025. To investigate this localized rainfall event, the present study utilized rain-gauge (IMD), satellite observations (MODIS) and ERA5 reanalysis datasets. Findings revealed a strong gradient in mean sea level pressure, negative values of vertically integrated moisture divergence, and enhanced convective precipitation over the selected region, inferred development and evolution of deep, moisture-laden convective processes. Simultaneously, elevated convective available potential energy (200–650 J/kg) and reduced convective inhibition (0–50 J/kg) confirm enhanced atmospheric instability favourable for intense convection. Cloud properties showed an increase in cloud effective radius (30–40 µm), cloud liquid water path (450–1100 g/m2), cloud optical thickness (18–50), cloud top height (7–15 km) and decrease in cloud base height (0.2–0.6 km) during 15–18 August. The integrated approach revealed that moisture convergence, thermodynamic instability and efficient energy transfer resulted in a heavy downpour. These variations in cloud properties and unstable local conditions can be used as inputs in regional weather models, to improve forecasting of heavy-extreme rainfall events.