Abstract The effect of Sudden Stratospheric Warming (SSW) event of January 2008 on the Equatorial Ionosphere-Thermosphere System (EITS) over Trivandrum (8.5°N, 77°E, 0.5°N diplat.), a geomagnetic dip equatorial station in India has been investigated. It has been observed that the entire EITS exhibits significant variability during the SSW period. EITS parameters like Equatorial Electrojet (EEJ), F2 layer critical frequency (foF2), F1 layer base height (h'F), Total Electron Content (TEC) and 630nm thermospheric dayglow showed clear cut signatures of the SSW induced effects. It is suggested that dynamical perturbations associated with the SSW and subsequent modifications in the tidal components through wave–tidal interactions are responsible for such changes in the equatorial electrodynamics. The present study comprehensively brings out the quiet time equatorial ionosphere/thermosphere variability, during both night and daytimes, vis-à-vis the SSW event of January 2008.