Hurricane Isabel was the costliest and deadliest hurricane in the 2003 Atlantic hurricane season. The ninth named storm and fifth 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 steadily strengthened to reach peak winds of 165 mph (265 km/h) on September 11. Isabel gradually weakened and made landfall on the Outer Banks of North Carolina with winds of 105 mph (165 km/h) on September 18, quickly weakening over land and became extratropical over western Pennsylvania the next day.
The worst effects of Isabel occurred in Virginia, especially in the Hampton Roads area and along the shores of rivers as far west and north as Richmond and Washington, DC. Electric service was disrupted in areas of Virginia for several days, some more rural areas were without electricity for weeks, and local flooding caused thousands of dollars in damage. Overall, roughly six million people overall were left without electric service in the eastern United States and damage totalled about $5.7 billion (2003 USD, $9.44 billion 2024 USD). 16 deaths in seven U.S. states were directly related to the hurricane, with 35 deaths in six states and one Canadian province indirectly related to the hurricane.