During the last 50 years, storm surge has accounted for nearly half the deaths associated with landfalling tropical systems, yet there was no warning system in place. In 2017, the National Weather Service began implementing storm surge watches and warnings so people could better prepare for this danger.

A storm surge warning is issued when there is a danger of life-threatening inundation from rising water moving inland from the coastline, typically within the next 36 hours. It’s one of the most serious warnings issued during a tropical storm or hurricane and is often a key factor in evacuation decisions for coastal communities.

Storm surge occurs when strong winds from a storm, especially tropical systems, push ocean water onto land, often on top of already high tides. This push of water can cause extreme flooding, even in areas that aren’t directly hit by the storm’s center. The water doesn’t just rise slowly like in a typical flood; it can push in rapidly, damaging homes, roads and critical infrastructure.

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The warning area will be clearly defined by the National Hurricane Center (NHC) and local National Weather Service offices, based on forecast models that take into account the storm's strength, size, speed and the shape of the coastline. A storm surge warning means you should take immediate action, stay informed, follow local evacuation orders and prepare for dangerous flooding — not just from rainfall, but from the ocean itself.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.