Why the nor'easter’s storm surge was so high, and what it says about the El Niño winter ahead

A powerful nor’easter hit the U.S. Atlantic Coast in late September 2026, causing severe flooding from North Carolina to New York. The flooding was driven by a combination of factors, primarily a storm surge, which occurs when strong winds push ocean water toward the shore. As the nor’easter intensified, its winds grew stronger, and the low atmospheric pressure (the force exerted by the weight of the air) also contributed to the surge. The storm’s slow movement along the coast meant the surge lasted longer, worsening the flooding. The surge was especially high in shallow bays and inlets, where water becomes concentrated and has nowhere to go but onto land. For example, Raritan Bay in New Jersey and Delaware Bay experienced some of the largest surges during the storm.

The flooding was made worse by high tides, which occur due to the gravitational pull of the Moon and the Sun. During a full moon, the combined gravitational forces create higher-than-normal tides, a phenomenon known as spring tides. The nor’easter struck during such a period, amplifying the flood risk. Additionally, the storm lasted for multiple high tides, leading to repeated rounds of flooding. The inundation—the actual water level above ground—was the result of both the storm surge and the tide. When the peak surge coincided with high tide, the flooding was at its worst. This combination of factors is what led to historic water levels in places like Atlantic City, New Jersey, where the water reached its highest point since Superstorm Sandy in 2012.

Rising sea levels are making coastal flooding more likely, even during storms that might not have caused major flooding in the past. Sea levels are rising due to global warming, which causes glaciers to melt and adds more water to the oceans. Additionally, the ocean itself expands as it warms. Along the U.S. East Coast, sea levels are rising faster than in other regions due to a process called post-glacial rebound. Thousands of years ago, a massive ice sheet covered parts of North America, pushing the land down under its weight. When the ice melted, the land that had been pushed up around the edges, including the mid-Atlantic seaboard, began to sink again. In Atlantic City, sea levels are rising at a rate of about 2 inches (50 millimeters) every decade. Even small increases in sea level can mean the difference between water staying out of homes or flooding them during a storm.

A strong El Niño event is currently influencing global weather patterns, and this could affect the upcoming winter. El Niño is a climate phenomenon characterized by unusually warm ocean temperatures in the equatorial Pacific Ocean, which can alter weather patterns worldwide. Research suggests that strong nor’easters along the East Coast are more likely during El Niño years. Seasonal forecasts indicate an increased chance of above-normal precipitation along the East Coast this winter, meaning storms with heavy rain and damaging surges may be more frequent. However, every El Niño is different, and this event’s strength makes it difficult to predict exactly how it will impact the winter. Experts advise being prepared by checking insurance policies, having an emergency supply kit, and staying informed through trusted weather and emergency management sources.