Triboelectric nanogenerators (TENGs) are highly effective for harvesting low-frequency and stochastic environmental energy. However, realistic outdoor conditions involve multiple coexisting stimuli. The resulting environmental perturbations disrupt rotor motion, which compromises the efficiency and stability of triboelectric charge transfer. Here, we report a raindrop-assisted aerodynamically activated triboelectric nanogenerator (RA-TENG) that leverages wind-rain coupling to enhance mechanical driving rather than treating rainfall as a detrimental factor. In this system, raindrop-induced momentum transfer actively modulates the rotational dynamics of the turbine, leading to a reduced activation threshold and improved rotational continuity. As a result, the frequency and stability of the device operation are significantly enhanced, thus reinforcing charge excitation and increasing charge transfer. The RA-TENG exhibits a low start-up wind speed of 3 m/s under wind-only conditions, which can be further reduced to 1.9 m/s under wind-rain excitation. At a wind speed of 6 m/s, the transferred charge of the device under combined wind-rain excitation is increased by 42% compared with that under single wind driving. This work establishes a mechanical-electrical coupling strategy and providing a general framework for converting environmental perturbations into constructive driving forces.