When people think of hurricanes they picture wind. But historically, water has caused most hurricane deaths in the US, and storm surge is the biggest single cause, according to the National Hurricane Center.
What storm surge is
Storm surge is an abnormal rise of sea water pushed ashore by a storm’s winds. It is measured as the height of water above the normal predicted tide. When surge arrives at high tide, the combined rise, called the storm tide, is even higher.
Surge can come in fast, flooding streets within minutes, and it carries debris that batters buildings.
How high it gets
- Hurricane Katrina (2005) pushed surge of about 28 feet onto the Mississippi coast, one of the highest recorded in the US.
- Hurricane Ike (2008) brought surge of 15 to 20 feet to parts of the upper Texas coast, including the Bolivar Peninsula.
- Hurricane Ian (2022) caused surge of 10 to 15 feet in parts of Lee County, Florida, including Fort Myers Beach.
What makes surge worse
- Storm size: a wide storm pushes water over a larger area, even if its winds are not the strongest.
- Shallow coastline: gently sloping sea floors, like much of the Gulf Coast, let water pile up.
- Bays and inlets: funnel-shaped coastlines concentrate water.
- Angle and speed at which the storm hits the coast.
This is why a Category 1 or 2 storm can still bring a deadly surge.
Who is at risk
Low-lying areas along the Atlantic and Gulf coasts face the most surge risk. FEMA’s National Risk Index tracks this mostly under coastal flooding and hurricane. You can check both ratings, plus past hurricane declarations, on any coastal county’s page.
Florida, Louisiana and Texas have the largest populations in surge-prone areas, but parts of every Atlantic and Gulf state are exposed, as Hurricane Sandy showed in New York and New Jersey in 2012.
How to protect yourself
- Know your evacuation zone. Coastal counties publish evacuation zones based on surge risk, not distance from the beach. Look yours up before hurricane season.
- Leave when told. Surge is the main reason officials order evacuations. Even sturdy buildings can be flooded.
- Buy flood insurance. Surge damage is flood damage, and standard home insurance does not cover it. Remember the 30-day waiting period.
- Watch the surge warnings. The National Hurricane Center issues storm surge watches and warnings separate from wind warnings.
Questions people ask
Is storm surge the same as a tsunami? No. A tsunami is caused by an undersea earthquake or landslide. Storm surge is caused by wind and low pressure from a storm.
Does a higher-category storm always bring a bigger surge? No. The category is based only on wind speed. A large, slower Category 2 can bring a bigger surge than a compact Category 4.
How far inland can surge reach? In flat, low areas, surge can push many miles inland, especially up rivers and bays.