The 2003 Atlantic hurricane season was a very active season with tropical cyclogenesis occurring before and after the official bounds of the season—the first such occurrence since the 1970 season. The season produced 21 tropical cyclones, of which 16 developed into named storms; seven of those attained hurricane status, of which three reached major hurricane status. The strongest hurricane of the season was Hurricane Isabel, which reached Category 5 status on the Saffir–Simpson hurricane scale northeast of the Lesser Antilles; Isabel later struck North Carolina as a Category 2 hurricane, causing $3.6 billion in damage and a total of 51 deaths across the Mid-Atlantic region of the United States.

Hurricane Isabel was the strongest Atlantic hurricane since Mitch, and the deadliest, costliest, and most intense hurricane in the 2003 Atlantic hurricane season. Hurricane Isabel was also the strongest hurricane in the open waters of the Atlantic, both by wind speed and central pressure, before being surpassed by hurricanes Irma and Dorian in 2017 and 2019, respectively. The ninth named storm, fifth hurricane, and second major hurricane of the season, Isabel formed near the Cape Verde Islands from a tropical wave on September 6, in the tropical Atlantic Ocean. It moved northwestward, and within an environment of light wind shear and warm waters, it steadily strengthened to reach peak winds of 165 mph (266 km/h) on September 11. After fluctuating in intensity for four days, during which it displayed annular characteristics, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina, with winds of 105 mph (169 km/h) on September 18. Isabel quickly weakened over land and became extratropical over western Pennsylvania on the next day. On September 20, the extratropical remnants of Isabel were absorbed into another system over Eastern Canada.