The performance of dielectric barrier discharge (DBD) ozone generators is strongly influenced by environmental conditions, yet the underlying mechanisms remain insufficiently quantified. In this work, a controlled-climate experimental platform and an AC-modulated surface dielectric barrier discharge (SDBD) reactor were developed to investigate the independent effects of gas temperature and humidity on ozone production. Measurements conducted at 10–50 °C and 40–90% relative humidity under fixed excitation conditions show that both parameters significantly suppress ozone accumulation, reducing the maximum generation rate and energy efficiency. Increasing temperature shortens the lifetime of reactive oxygen species and enhances thermal ozone decay, while humidity introduces additional electron-energy-loss channels and promotes the formation of OH radicals that accelerate ozone destruction. Zero-dimensional plasma-chemical simulations corroborate the experiments by revealing the temperature-dependent reduction in ozone stability and the humidity-driven rise of OH concentrations that dominate ozone-loss kinetics. The combined results clarify how environmental factors reshape the balance between ozone formation and depletion, providing a mechanistic basis for optimizing SDBD ozone generators and developing adaptive strategies to maintain stable output under fluctuating ambient conditions.