What is Coastal Flooding?
While flash flooding can occur anywhere from heavy rains and poor drainage, coastal flooding occurs when intense, offshore low-pressure systems drive ocean water inland. The water pushed ashore is called storm surge.
Coastal Flooding and New York City
The effects of the tides, combined with large amounts of water and waves from storms, place some areas in the five boroughs of New York City at risk for coastal flooding.
To learn more about coastal flood risk in New York City, visit the FEMA Region II Coastal Analysis and Mapping website for flood hazard information.
National Weather Service Terms
- COASTAL FLOOD WATCH: Issued by the National Weather Service when coastal flooding is possible within 12 to 36 hours.
- COASTAL FLOOD WARNING: Issued by the National Weather service when coastal flooding is occurring, imminent, or expected within 12 hours.
Coastal Flooding Levels
Coastal flooding levels — categorized as minor, moderate, or major — are calculated based on the amount water rises above the normal tide in a particular area.
Minor flooding is nuisance coastal flooding of locations adjacent to the shore. Minor beach erosion can occur. Minor coastal flooding is not expected to close roads or do any major structural damage to homes and other buildings.
Moderate flooding is more substantial coastal flooding, threatening life and property. Some roads may become impassable due to flooding. Moderate beach erosion will occur along with damage to some homes, businesses, and other facilities.
Major flooding is a serious threat to both life and property. Numerous roads will likely become flooded. Many homes and businesses along the coast will receive major damage. People should review safety precautions and prepare to evacuate if necessary. Major beach erosion is also expected.
During a Flood
If it is safe to evacuate by car:
- Take your Go Bag with you.
- Avoid flooded roadways. Parts of the road may already be washed out, and you could become stranded or trapped.
- If your car stalls in a flooded area, abandon it as soon as possible. Floodwaters can rise rapidly and sweep a car (and its occupants) away.