Increased North Atlantic Tropical Cyclone Risk in the Wake of a "Super" El Niño Event

Nicolas Bruneau, Richard Dixon, Daniel L. Swain, Hannah Croad, Thomas Loridan

The El Niño-Southern Oscillation (ENSO) is among the most influential modes of climate variability on Earth, dramatically reshaping global weather patterns. It is therefore a key driver of regional extremes and has been recognized as a key risk predictor for a wide range of natural hazards, from drought and wildfire to extreme rainfall and flooding. Considerable attention has been paid to the role El Niño plays in suppressing same-season North Atlantic hurricane activity, but relationships at longer lead times have been less studied despite considerable potential preparedness and planning implications. In 2026, multi-model predictive ensembles are indicating a high likelihood of an exceptionally strong El Niño event by autumn, offering a rare opportunity to deliver new insights regarding muti-year hurricane risk with near real-time relevance. Here, we report findings drawn from a tropical cyclone probabilistic event set conditioned by large ensemble climate model simulations (CESM2-LENS). We find that strong El Niño events more than double the baseline likelihood (+120%) of La Niña conditions in the subsequent year, and are therefore a leading (year-ahead) indicator of increased United States hurricane landfall risk. Based on current (June 2026) operational ENSO forecasts, we further find that the risk of US landfalling major hurricanes in 2027 may be considerably higher than baseline (+23%) following decreased risk in 2026 (-28%). These are actionable findings across both the public and private sectors, which have expressed growing interest in physically grounded, multi-year risk estimates to inform timely decisions beyond the present year.