Guides

Understanding Coastal Flood Alerts: Essential Information for Coastal Residents

June 18, 2026 · The Clime Team

Coastal flooding poses significant risks to communities along the nation's shorelines. Understanding the various coastal flood alerts and the appropriate safety measures is crucial for residents.

What Are Coastal Flood Alerts?

Coastal flood alerts are official notifications issued by meteorological agencies, such as the National Weather Service (NWS), to inform the public about potential or occurring flooding along coastlines. These alerts are categorized into three primary levels:

Coastal Flood Advisory: Indicates minor coastal flooding is expected or occurring, which may cause inconvenience but is not expected to pose a serious threat to life or property.
Coastal Flood Watch: Signifies that moderate to major coastal flooding is possible, posing a serious risk to life and property.
Coastal Flood Warning: Denotes that moderate to major coastal flooding is occurring or imminent, posing a serious threat to life and property.

What Causes Coastal Flooding?

Coastal flooding can result from various factors, including:

High Astronomical Tides: Naturally occurring high tides, such as spring or king tides, can elevate water levels, leading to flooding.
Storm Surge: Strong coastal storms can push large volumes of water onto the land, causing significant flooding.
Heavy Rainfall: Excessive rainfall, especially when combined with high tides, can overwhelm drainage systems and exacerbate flooding.
Persistent Onshore Winds: Continuous winds blowing towards the coast can push water inland, leading to elevated water levels.

How Are Coastal Flood Alerts Issued?

The NWS issues coastal flood alerts based on forecasts and observations of conditions that could lead to flooding. These alerts are disseminated through various channels, including:

NOAA Weather Radio: Provides continuous broadcasts of official Weather Service information.
Emergency Alert System (EAS): Delivers emergency information via broadcast, cable, satellite, and wireless communications.
Wireless Emergency Alerts (WEA): Short emergency messages sent by authorized authorities to alert the public about emergencies in their area.

What Should Residents Do When a Coastal Flood Alert Is Issued?

Residents should take the following actions based on the type of alert:

Coastal Flood Advisory:
Be aware of the potential for minor flooding.
Avoid driving through flooded areas.
Secure outdoor items that could be affected by rising waters.
Coastal Flood Watch:
Stay informed by monitoring local weather updates.
Prepare for possible evacuation if conditions worsen.
Move vehicles and valuables to higher ground.
Coastal Flood Warning:
Follow evacuation orders promptly.
Avoid all coastal areas and seek higher ground immediately.
Stay tuned to official channels for updates and instructions.

How Does Sea Level Rise Affect Coastal Flooding?

Global sea level rise is causing coastal flooding to occur more frequently along much of the U.S. East Coast. According to a report from the Environmental Protection Agency, coastal flooding is now at least five times as likely for many of the sites examined compared to the 1950s. As sea levels continue to rise, areas that rarely experienced coastal flooding may begin to see it more often, and regions that have never experienced it could suddenly face this new threat. (weather.com)

What Are the Different Levels of Coastal Flooding?

Coastal flooding is categorized into four levels based on severity:

Minor: Nuisance flooding that does not pose a significant threat to life or property.
Moderate: Flooding that begins to inundate the lowest homes and businesses and roads.
Major: Significant flooding of structures, roads, and life-threatening conditions.
Record: Higher than ever recorded flooding levels.

How Accurate Are Coastal Flood Warnings?

The accuracy of coastal flood warnings has improved significantly over the past decade. Advancements in forecasting models and technology have enhanced the ability to predict and monitor coastal flooding events. However, it's important to always allow flexibility in your response for a more substantial tidal flood than expected. (weather.gov)

How Can I Protect My Home from Coastal Flooding?

To safeguard your property from coastal flooding:

Elevate Structures: Raise the elevation of your home or business above the base flood elevation.
Install Flood Barriers: Use flood shields or barriers to prevent water from entering your property.
Seal Openings: Seal cracks and openings in walls and foundations to prevent water intrusion.
Landscaping: Grade your property to direct water away from structures.
Emergency Kit: Prepare an emergency kit with essentials like food, water, medications, a flashlight, and a first-aid kit.

What Should I Do After a Coastal Flood?

After a coastal flood:

Stay Informed: Monitor local news and official channels for updates.
Avoid Floodwaters: Do not enter floodwaters, as they may contain debris, chemicals, or sewage.
Inspect Property: Check your property for damage and document it for insurance purposes.
Follow Official Guidance: Adhere to instructions from local authorities regarding safety and recovery efforts.

Understanding coastal flood alerts and taking appropriate actions can significantly reduce the risks associated with coastal flooding. Stay informed, prepared, and vigilant to protect yourself and your community.

Highlights:

Coastal Flood Alerts Explained: A Worsening Threat That Can Happen Even When The Sun Is Shining | Weather.com, Published on Sunday, September 14
Coastal Flood Safety Rules
Identify Weather Threats Tidal Flood