Seasonal Drivers of Storm Tides and Coastal Flood Impacts Along the US Atlantic Coast

Due to sea‐level rise, densely populated coastal areas are facing increasing flood risk during coastal storms. Much of the US East Coast experiences extratropical cyclones (ETCs) more frequently than tropical cyclones (TCs), yet many studies on extreme flood risk focus primarily on TCs or exclude ETCs altogether. ETCs occur primarily during November to April (henceforth, the cool season), while TCs occur primarily during May to October (henceforth, the warm season). This study performs a quasi‐nonstationary skew surge joint probability (qn‐SSJPM) analysis of storm tide exceedance distributions for cool and warm seasons from 23 tide gauges along the US East Coast to assess seasonal contributions to extreme sea levels. From Boston, MA northward, cool‐season extreme storm tides predominate, while south of Wilmington, NC, warm‐season storm tides predominate. Using an illustrative property damage curve, we show that, for New York City, cool‐ and warm‐season storms cause comparable amounts of average annual property damage. These findings highlight the importance of treating cool‐ and warm‐season storms as statistically separate to improve flood risk analysis.