Hurricane Florence was a powerful and long-lived Cape Verde hurricane that caused catastrophic damage in the Carolinas in September 2018, primarily as a result of freshwater flooding due to torrential rain. The sixth named storm, third hurricane, and the first major hurricane of the 2018 Atlantic hurricane season, Florence originated from a strong tropical wave that emerged off the west coast of Africa on August 30, 2018. The wave steadily organized, and strengthened into a tropical depression on the next day near Cape Verde. Progressing along a steady west-northwest trajectory, the system gradually strengthened, acquiring tropical storm strength on September 1. An unexpected bout of rapid intensification ensued on September 4–5, culminating with Florence becoming a Category 4 major hurricane on the Saffir–Simpson scale (SSHWS), with estimated maximum sustained winds of 130 mph (215 km/h). Strong wind shear then led to rapid weakening, and Florence weakened to tropical storm strength on September 7. Shifting steering currents led to a westward turn into a more suitable environment; as a result, Florence reintensified to hurricane strength on September 9 and major hurricane status by the following day. Florence reached peak intensity on September 11, with 1-minute winds of 150 mph (240 km/h) and a minimum central pressure of 937 mbar (27.7 inHg). An unexpected eyewall replacement cycle and decreasing oceanic heat content caused a steady weakening trend; however, the storm grew in size at the same time. Early on September 14, Florence made landfall in the United States just south of Wrightsville Beach, North Carolina as a Category 1 hurricane, and weakened further as it slowly moved inland under the influence of weak steering currents. Florence degenerated into a post-tropical cyclone over West Virginia on September 17 and was absorbed by another frontal storm two days later.

The 2018 Atlantic hurricane season was the third in a consecutive series of above-average and damaging Atlantic hurricane seasons, featuring 15 named storms, 8 hurricanes, and 2 major hurricanes, which caused a total of over $50 billion in damages and at least 172 deaths. More than 98% of the total damage was caused by two hurricanes. The season officially began on June 1, 2018, and ended on November 30, 2018. These dates historically describe the period in each year when most tropical cyclones form in the Atlantic basin and are adopted by convention. However, subtropical or tropical cyclogenesis is possible at any time of the year, as demonstrated by the formation of Tropical Storm Alberto on May 25, making this the fourth consecutive year in which a storm developed before the official start of the season. The season concluded with Oscar transitioning into an extratropical cyclone on October 31, almost a month before the official end.