<p>Dayet Aoua, a key freshwater lake in the Middle Atlas region of Morocco, has undergone significant hydrological fluctuations over the past decades due to climate variability. This study investigates the long-term hydro-climatic trends affecting the lake’s water balance, focusing on precipitation variability, temperature fluctuations, and evapotranspiration dynamics. Using meteorological and hydrological data spanning from 1935 to 2022, statistical methods, including the Mann––Kendall test and Pettitt’s change-point analysis, were applied to assess trends in precipitation, temperature, and lake water levels. The results indicate a significant decline in water levels, primarily driven by decreasing precipitation and increasing evapotranspiration rates. A structural shift in precipitation patterns was detected in 1972, with a notable reduction in annual rainfall. Simultaneously, a consistent warming trend of 0.43°C per decade and an annual evapotranspiration increase of 5.56 mm have intensified hydrological imbalances, leading to recurrent desiccation events. These findings emphasize the vulnerability of high-altitude freshwater ecosystems to climate-induced stressors and highlight the need for improved climate monitoring and hydrological modeling. Future research should incorporate high-resolution climate datasets to refine water balance assessments and enhance adaptive management strategies for similar Mediterranean lake systems.</p>