With Ida in many residents’ minds, it’s useful to look at the latest maps of predicted flooding if another hurricane hits NYC.

New York City is facing multiple climate hazards that will impact daily life in the City in the future. Coastal storms, heat waves, sea level rise impacts, and extreme rain will strain our infrastructure and put New York City’s homes and businesses at risk. As climate change continues, these impacts are predicted to worsen in the coming decades.

The Stormwater Resiliency Plan and associated rainfall maps (beta) are the first City-wide analysis of how extreme rainfall will impact New Yorkers now and into the coming decades. The Plan also establishes key goals and initiatives for the next 10 years to ensure future investments made by City agencies consider and address impacts on rain-driven flooding vulnerability. The Plan and maps will be updated at minimum every four years. Read the Stormwater Resiliency Plan here: nyc.gov/resiliency

The maps focus on rain because it is by far the most common cause of precipitation-based flooding in NYC (as compared to other forms of precipitation, such as snow or sleet). Flooding caused by rainfall is more difficult to map than flooding from coastal storms like Hurricane Sandy. Unlike coastal flooding caused by hurricanes and Nor’easters, rainfall-based flooding can be caused by isolated storms in both waterfront and inland areas. Some may remember the heavy rains that fell in July of 2019. At the peak of the storm, the City’s weather stations recorded rates of almost five inches of rain per hour in central and northern Brooklyn. This resulted in flooding deeper than one foot in several locations across the City. By the 2080s, we know that extreme rain events are predicted to become 1.5 times more likely than today, and sea level will continue to rise by as much as 6 feet. Many of our sewers end up draining at or near coastal waters. As sea level rises, our sewer system cannot drain properly. On top of these stressors, NYC is similar to other cities in the US in that it is working with a sewer network first constructed decades ago, when we did not expect this amount and intensity of rainfall. By publishing this Plan and maps, the City is working to prepare for a future where extreme storms are more common.

The first map (below) shows what a moderate rainfall’s impact is predicted to be (darker blue meaning flooding more than 1 foot in the neighborhood: