Compared to the historical period (2009–2014), the RCA4 model predicts a decrease in precipitation in the near future (2022–2060) in the NRB, with an increase in the distant future (2061–2100), regardless of the emission scenario considered (Figures 10 and 11). Over the period 2022–2060, the decreases are projected respectively under the RCP4.5 and RCP8.5 scenarios as –6 and –9.6% (Table 9). According to the model, the decrease in precipitation over this interval will be mainly caused by a decrease in summer and autumn precipitation since the other two seasons (spring and winter) will experience an overall increase (Figure 10). The 2020 and 2030s appear according to the model forecasts to be the driest of the century under the RCP8.5 scenario. Under the RCP4.5 scenario, this situation concerns the 2020 and 2040s (Figure 11). Between 2061 and 2100, the RCA4 model predicts, unlike the first period (2022–2060), a significant increase in precipitation in the basin under the scenarios RCP4.5 (+18.5%) and RCP8.5 (+34.3%)) (Table 9). This increase will mainly result from an increase in winter and spring precipitation (Figure 10). The 2070 and 2090s are projected to be the wettest decades of the century under the RCP8.5 scenario. Under the RCP4.5 scenario, the 2080 and 2090s will be the wettest decades (Figure 11).