This article presents the results of a long-term field experiment (1990–2024) investigating pea yield under changing climatic conditions in the Rostov Region, Russia. Given the high demand for pea in both Russia and the Rostov Region, maximizing yield is a primary objective of agricultural production. The study aimed to determine the optimal combination of hydrothermal factors (temperature, precipitation) influencing the yield of pea varieties in the Azov zone of the Rostov Region. A comparative analysis was conducted to assess pea productivity during vegetation periods characterized by contrasting climatic conditions (drought vs. wet). The study also quantified yield fluctuations (1.65–2.70 t/ha) in relation to varying fertilizer application rates and climatic conditions. During drought periods, pea yield decreased by 8.3%, whereas during wet periods, it increased by 11.0% compared to long-term average values. Optimal temperature and precipitation ranges for maximizing pea yields were identified as 14.0–17.5°C and 200–300 mm, respectively. Fertilizer profitability was reduced by 15.3–22.8% during wet vegetation periods compared to drought years. An optimal temperature range of 15.5–17.5°C and precipitation of 200–300 mm during the vegetation period were also identified for maximizing fertilizer profitability, resulting in yield increases of 6.00–7.00 kg/kg with a higher application rate (P80K80). Application of varying fertilizer rates can enhance fertilizer efficiency and compensate for the adverse effects of climatic conditions.