<p>Large-scale atmospheric variability, occurring over sub-seasonal (10–90 days) to inter-annual (≥ 91 days) timescales, significantly influences the formation, intensity, and movement of tropical cyclones. Nevertheless, the individual and combined effects of these modes on tropical cyclone dynamics remain insufficiently explored. This study investigates how the interaction of these modes of variability across different timescales as synergistically or in isolation under the mean background environment, modulating the movement of two pre-monsoon tropical cyclones over the Bay of Bengal using the Weather Research and Forecasting (WRF-ARW) model. Our analysis based on streamline flows, vorticity budget, and subsequent moisture response processes shows that sub-seasonal atmospheric variability, ranging from quasi-biweekly (10–20 days; QBWOs) to intra-seasonal (20–90 days; ISOs) timescales, plays a critical role in determining the cyclone tracks. The evolution of large-scale streamline flows reveals that, variations in the evolution of mid-latitude troughs and anticyclonic circulation arose due to an interaction of sub-seasonal flow fields with the mean background environment and eventually leads to cyclone track deflections. Further, vorticity budget analysis suggests that, beyond horizontal advection, tilting processes induced by sub-seasonal variability also significantly contribute to the vortex development, ultimately influencing the observed cyclone paths. Our findings clearly suggest that pre-monsoon tropical cyclone track prediction on sub-seasonal timescales can be better achieved by accurately incorporating sub-seasonal flows and their variability into the numerical models.</p>