Storm surge is sea-level rise on top of the normal tide level. The rise in sea level, is created by low-pressure systems, including tropical cyclones as they near the coast. If storm surge arrives during low tide, coastal impacts may be minor. If however, storm surge arrives during a high tide, the impacts can be much more severe. The large waves accompanying low pressure systems, can make coastal and structural damage much worse. Storm surge, combined with large waves can reach areas far away from the coast.

Strong low pressure systems, especially tropical cyclones, create storm surges by physically pushing the water onshore. The stronger the winds, the higher the storm surge. Large storm surges can push water many kilometres inland. Which, combined with wind and pounding waves, can destroy buildings, wash away roads and pose threat to life.