The surge process, magnitude and timing are of critical importance for accurate storm prediction and warning as well as hazard mitigation. A total of 28 tropical cyclones that most affected the head Bay of Bengal during 1991−2020 are selected and simulated with interactive forces including wind, tide, wave and river discharge. The occurrence frequencies of the maximum surge cluster in the rising tide, amounting to 89.3%, mostly 3 h and 4 h before the peak tide. The larger maximum surges are associated with phase shift of storm tide from astronomical tide. The surge processes can be classified into “(quasi-) solitary wave” and “(quasi-) periodic” oscillations. The solitary-wave-like surge may last only the rising tide or both the rising tide and the falling tide. The non-linear interactions between the storm surge and astronomical tide have the same period of a semi-diurnal tide, and their amplitudes are controlled by tidal range. The surge-tide interaction curves demonstrate two types: one is “peak in rising tide and trough in falling tide”, the other is the opposite. They are 180°out of phase, i.e. 6 h for a semi-diurnal tide. The advancing direction of cyclones relative to tidal current, the tidal phase at a cyclone landfall and the formation & propagation of trapped edge surge waves are the dominant mechanism to determine the timing of maximum surges.