Understanding the hydrological-geochemical impacts on rare earth elements (REEs) in riparian zones is critical for sustainable pollution management under intensifying climate extremes. This study decoded seasonal regulatory mechanisms governing REE dynamics in a semi-arid riparian zone overlying the Maoniuping deposit, revealing that natural processes can be leveraged for low-energy remediation. The findings indicated that seasonal thermal-hydrologic fluctuations resulted in distinct geochemical microenvironments that governed REE mobility and fate. In surface water (SW), REE enrichment was dominated by runoff and precipitation inputs during wet season, whereas shallow groundwater (SGW) exhibited intensified REE accumulation in the dry season due to prolonged water-rock interactions under elevated temperatures and reduced water levels. Multivariate analyses revealed that REE concentrations in SW were strongly associated with adsorption onto Al-Fe-Mn colloids. In contrast, REE dynamics in SGW during the wet season were significantly influenced by temperature, water level, Al, Fe, Mn, HCO3- , SO42- , and NO3- , while dry-season dynamics were primarily governed by temperature and Al alone. Water level indirectly suppressed REE release by enhancing HCO3- and non-polar organic compounds (NPOC) levels while reducing the level of oxidation-reduction potential (ORP). Temperature exerted control through its effects on NPOC and ORP. Notably, seasonal partitioning patterns also shifted markedly in groundwater: particulate and colloidal phases prevailed under dry conditions, whereas dissolved REE fractions increased significantly during the wet season. These findings established a mechanistic framework linking climate variability to REE mobilization through cascading biogeochemical processes, offering scientific support for adaptive, low-energy strategies to mitigate REE contamination in mining-impacted riparian systems.