Storm Surge Explained
Storm surge is the abnormal rise in seawater during a hurricane, pushed onshore by the storm's wind and pressure. It is not a wave. It is a dome of water that can be 15 to 20 feet high and extend miles inland, and it is the deadliest part of any hurricane. More than half of all hurricane deaths in the United States are directly caused by surge.
Surge height depends on the storm's intensity, size, forward speed, angle of approach, and the shape of the coastline. A shallow continental shelf, like the Gulf Coast, piles water higher than a steep shelf. A storm arriving perpendicular to the coast pushes more water than one skimming parallel. The right-front quadrant of the storm, relative to its direction of motion, has the strongest onshore winds and the worst surge.
How high can it get
- Katrina (2005) produced about 28 feet at Pass Christian, Mississippi, the highest surge ever recorded in the United States.
- Ian (2022) pushed 10 to 15 feet across Fort Myers Beach and Pine Island.
- Helene (2024) set the Tampa Bay record at 6 to 8 feet from more than 100 miles offshore.
Are you at risk
If you live within 30 miles of the Gulf or Atlantic coast and your elevation is below 30 feet, you are in a potential surge zone. Evacuation zones A through E are assigned by surge risk. If you are in Zone A, you will be ordered out for almost any storm. Look up your zone before the season starts.
Find your state's zone lookup →
Why surge kills
Six inches of moving water can knock an adult down. Two feet can float a car. Surge arrives with debris, including boats, vehicles, and structural pieces, that act as battering rams. People who survive the initial rise can be trapped in attics as the water keeps climbing, which is what happened in Katrina. If you are in an ordered zone, leave. Do not wait to see the water.