Storm surge: What is it and what are the effects?
By Allstate
Last updated: October 2023
One of the greatest threats during a hurricane doesn't just come from high winds, but from a flooding event known as a storm surge. Here's a look at what a storm surge is and some tips to help you stay safe if one threatens your area.
What is a storm surge?
The National Oceanic and Atmospheric Administration (NOAA) describes a storm surge as a rise in seawater level that's caused by a storm. It occurs when powerful winds from a hurricane, tropical storm or even a winter storm push ocean water ashore. This creates a rise in seawater level that's greater than the predicted tide.
A storm surge is measured by the height of water above the expected tide, says NOAA.
Where can a storm surge happen?
Coastal areas are at risk for storm surges, says the National Weather Service (NWS). But, it's not just the immediate coastal areas that face the threat. Storm surges can also affect communities that are inland, adds NWS. In some instances, storm surges have penetrated inland areas 30 miles away from the coast.
What factors determine the size of a storm surge?
As with storms, not all storm surges are alike. The strength of a storm surge can vary according to a number of factors, including the size, speed and intensity of the storm, says the National Hurricane Center (NHC). The angle of the storm's approach and the shape of the coastline are also factors in the size of a storm surge. For example, a storm surge will likely be lower if the storm moves parallel to the coast, says NWS.
Storm surge levels can also be affected by the frequency of waves or the rise of rivers and streams due to heavy rainfall that often accompanies a storm, according to NWS.
What are the effects of a storm surge?
Regardless of what's predicted, it's important not to underestimate the potential danger of a storm surge. The NHC says storm surges can cause water levels to rise in a matter of minutes, leaving you little time to seek higher ground. Extreme flooding stemming from a storm surge can force major evacuations and may leave behind damage at your home.
A surge's strong waves and rushing water can erode beaches and coastal highways, says the NHC. Storm surges can also damage boats and marinas and kill vegetation due to the intrusion of salt water.
A storm surge can create a dangerous situation for you and your family, so it's important to be prepared. Consider creating an evacuation plan and packing an emergency "go bag" ahead of time so you can quickly depart if a storm surge forces you to evacuate.