Helene — 2024

Helene formed from a broad Central American circulation that organized into a tropical storm on 24 September 2024 about 175 nautical miles south of western Cuba. It moved northwestward into the Gulf of Mexico, strengthened to a hurricane near Cancun on 25 September, and then accelerated north-northeastward across the northeastern Gulf. The cyclone rapidly intensified on 26 September, developed a clear eye late that day, and moved ashore in the Florida Big Bend region on 27 September. After landfall it moved quickly inland across Georgia and the southern Appalachians, became post-tropical on 27 September, and dissipated over north‑central Tennessee on 28 September. Helene made a single U.S. landfall about 10 n mi southwest of Perry, Florida, around 0310 UTC 27 September 2024 as a major hurricane (see peak intensity below). Before becoming a hurricane Helene passed just east of the Yucatan and produced tropical-storm conditions in parts of northeastern Mexico and western Cuba on 24–25 September but did not make landfall there. The storm’s peak intensity was estimated at 120 kt (about 138 mph) with a landfall central pressure analyzed near 939 mb, making Helene a category 4 hurricane at peak. Aircraft reconnaissance measured flight-level winds that reduced to roughly 120 kt at the surface; the lowest pressures measured by dropsondes were around 941 mb. Storm surge was catastrophic along much of Florida’s Gulf Coast. Peak inundation of 12–16 ft above ground level (AGL) occurred from just west of Keaton Beach through Steinhatchee, with high water marks and deployed sensors confirming values above 13–16 ft in places. Cedar Key recorded 9.30 ft above mean higher high water (MHHW), the highest at that station since records began in 1914. Tampa Bay saw 5–7 ft AGL in places (East Bay measured 7.2 ft above MHHW; St. Petersburg recorded 6.31 ft above MHHW, a station record). Smaller but damaging storm surge (3–7 ft AGL) occurred along much of the west coast of Florida from the Big Bend south through Pinellas, Manatee and Charlotte counties. Rainfall was extreme from the Florida Panhandle north into the southern Appalachians: Busick, North Carolina recorded the highest total at 30.78 inches, with many locations in western North Carolina receiving 20–30 inches. Sumatra, Florida measured 14.39 inches, and parts of the Atlanta metro area saw 12–13 inches. Helene caused large loss of life and widespread destruction. Official reports attribute at least 175 direct deaths in the United States (14 from storm surge in Florida, 65 from wind, and 94 from freshwater flooding and landslides, with the largest freshwater-flood death toll in western North Carolina and eastern Tennessee) plus 72 indirect deaths and 3 of unknown cause, for a total of 250 fatalities linked to the event. Damage is preliminarily estimated at about $78.7 billion in the U.S., making Helene among the costliest U.S. hurricanes. Tens of thousands of structures were damaged or destroyed—entire communities in the Big Bend (Keaton Beach, Steinhatchee, Horseshoe Beach, Cedar Key) suffered catastrophic surge damage—and widespread tree damage and snapped power infrastructure left millions without electricity. Helene also produced 39 tornadoes (33 while tropical), including several strong and wide tornadoes, and triggered over 2,000 landslides in the southern Appalachians. Notable aspects include the storm’s very large wind field (34‑kt winds extended outward up to hundreds of nautical miles at times), its unusually rapid forward motion at landfall (about 27 kt), and its rapid intensification in the northeastern Gulf prior to landfall. Those factors combined to push damaging gusts far inland and to drive an extensive and record-setting storm surge footprint (for example, Cedar Key’s record water level). Forecast and warning products were used extensively; the report includes a detailed forecast and warning critique, but the factual highlights are the exceptional inland reach of hurricane‑force gusts and the extremely rare, catastrophic rainfall and river flooding in the southern Appalachians.