Storm surges pose significant threats to coastal communities, yet negative surges are not as well understood as positive surges. In this study, idealized experiments of a tropical cyclone forcing a 3D ocean model are conducted to investigate the asymmetry of positive and negative surges. Negative surges are larger in magnitude and extend further across the coastline than positive surges. While positive surges are driven by wind blowing onshore, negative surges are largely dominated by alongshore winds, with horizontal divergence as the main mechanism. This asymmetry also increases with decreasing depth and increasing latitude.