<p>This paper seeks to explore the relationship between the Somali Jet (SJ) and the Indian Summer Monsoon (ISM) during key periods to assess their influence on both the onset and withdrawal phases of the ISM, particularly before and after the climate shift of the year 1998. The present study investigates the variability in the onset and withdrawal phases, as well as the length of the monsoon season, across two distinct epochs: E1 (1975-1998) and E2 (1999-2022). The findings reveal a significant declining trend in onset and withdrawal durations of ISM during E2, resulting in uncertainty in the predictability of ISM. Interestingly, the season length is observed to be normal/longer in E2 even after a delayed onset, compensated by late withdrawal in E2, suggesting a shift in the monsoon season. We find this late onset and withdrawal of ISM associated with the weakening of the 850 hPa SJ in E2. Moreover, in the same period, a shift in SJ is also observed and might be attributed to the increased potential vorticity (PV) anomalies over the northern Arabian Sea. This enhanced PV indicates a strengthened monsoon vortex and intense cyclonic conditions favoring the SJ flow towards the northern region, avoiding peninsular India. Such a shift might potentially affect the moisture supply for a timely monsoon onset in May over Kerala (MOK). Conversely, observed strong SJ during September sustains the monsoon, resulting in late withdrawal. However, the correlation analysis suggests a weakening relationship between SJ and monsoon variables, suggesting increasing dominance of other factors in recent times.</p>