What is a storm surge?
Key points
- A storm surge is a dangerous rise in seawater pushed ashore by a storm, often causing flooding far beyond the expected tide — a core concept that sets up why this hazard matters.
- Storm surges can impact both coastal and inland communities, sometimes reaching 30 miles from the shoreline, highlighting how widespread the risk can be.
- The size of a storm surge depends on factors like storm intensity, speed, angle of approach, and coastline shape, helping readers understand why impacts vary.
- Storm surges can cause rapid, extreme flooding that leads to evacuations, property damage, and erosion, underscoring why preparation and evacuation planning are essential.
The National Oceanic and Atmospheric Administration (NOAA) describes a storm surge as a rise in seawater level that's caused by a storm. One of the greatest threats during a hurricane comes from how quickly a storm surge can push large amounts of water inland, creating dangerous flooding with little warning. Knowing how these surges behave and the risks they pose can help you stay prepared if one threatens your area.
What causes a storm surge?
Storm surges are caused by powerful winds from a hurricane, tropical storm or even a winter storm. These extreme weather events push ocean water ashore which 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.
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get a quoteWhat 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.