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 in New York City

• On April 16, 2011, strong winds acted to pile waters across the shoreline, causing widespread minor coastal flooding and areas of moderate coastal flooding during high tide. The highest tidal levels were recorded at southern Queens and along New York Harbor. Water levels rose to 5.64 feet in Queens, 8.68 feet in Staten Island, and 8.12 feet at the Battery.
• On March 13, 2010, the City experienced widespread moderate coastal flooding, with water levels reaching their highest levels in almost 20 years. Water rose to 12.36 feet at Kings Point, 8.5 feet at the Battery, and 8.7 feet at the Rockaway Inlet. This was 1.86 feet, 0.5 feet, and 0.2 feet above the moderate flooding benchmark, respectively. In addition, coastal flooding in Brooklyn prompted the closure of the Belt Parkway in both directions from Bay 8th Street to Bay Parkway.
• On April 16, 2007, a strong late season nor'easter impacted New York City with a prolonged period of moderate coastal flooding. A tide level of 11.57 feet was recorded at Kings Point, comparable to the tide levels during Hurricanes Gloria and Donna.
• In December 1992, a powerful nor'easter with hurricane-force winds left a mark on New York City as coastal flooding damaged as many as 20,000 homes and forced almost 2,000 people to take refuge in 36 Red Cross emergency storm shelters.

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.

New York City Areas and Coastal Flooding

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.

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.

For more information on coastal flooding, see the Hurricane Preparedness Guide, which is available in 11 languages
Find out if you live in a Hurricane Evacuation Zone