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

In 1991, the Halloween Nor'easter — popularized by the movie "The Perfect Storm" — stranded several southern Queens residents, as the primary Coastal Evacuation Route from the Rockaway Peninsula was inundated by coastal flooding.

In December 1992, another powerful nor'easter with hurricane-force winds left a mark on New York City when its flooding knocked out electrical service to city subways, forced LaGuardia Airport to close, and submerged parts of the FDR Drive in Manhattan in four feet of water. Coastal flooding from the nor'easter 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 — 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 — 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 — 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 Most at Risk of Coastal Flooding

Bronx: Edgewater Park, Silver Beach, Locust Point, Classon Point and Throggs Neck
Brooklyn: Coney Island, Brighton Beach, Manhattan Beach and Sheepshead Bay
Manhattan:

Queens: Rockaway Peninsula, Broad Channel, Howard Beach and West Hamilton Beach
Staten Island: New Dorp Beach, Oakwood Beach, Foxwood Beach, Great Kills and Tottenville

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 Hurricane Preparedness Guide, which is available in 11 languages
Find out if you live in a Hurricane Evacuation Zone