On the one hand, this study assesses the evolution of climatological parameters in the Zaër region between 1986 and 2021 and, on the other hand, it studies the effect of climatic variations on cereal and leguminous crop yields between 2000 and 2020, in order to further elucidate the consequences of their fluctuations on crop yields and to mitigate their regression process by making it possible to analyze favorable adaptation strategies for agricultural systems that can be envisaged for the coming decades. The methodology is based on the use of trend curves and statistics (averages and standard deviations) to analyze changes in climatic parameters and their effects on yields. The results show that the average temperature in the Zaër region is set to rise from 19°C in 1986 to 22°C in 2020. Higher temperatures mean lower yields of rainfed cereals and pulses, and average rainfall varies between 330 mm in 1986 and 570 mm in 2021, with rainfall increasing the likelihood of crop failure in the short term and reducing production in the long term. In addition, the rainy season is short (4 to 5 months per year). These characteristics make Zaër's agriculture very sensitive to climate-related threats. Studying seasonal climate forecasts before each rainy season can help farmers to minimize rainfall hazards and thus optimize their crop yields. Keywords: agriculture, climate change, semi-arid regions, crop yield, cultivated area.