Timeline of the 2003 Atlantic hurricane season

The 2003 Atlantic hurricane season was an active Atlantic hurricane season with tropical activity before and after the official bounds of the season – the first such occurrence in 33 years. The season officially began on June 1, 2003, and ended on November 30. However, a pre-season storm, Tropical Storm Ana, led to the season starting on April 20, and storm activity continued through December 11. This season had 21 tropical depressions, of which, 16 became named storms. Of these, 7 strengthened into hurricanes with 3 intensifying into major hurricanes. Hurricane Fabian, Hurricane Isabel, and Hurricane Juan had their names retired due to the impact caused in Bermuda, the eastern United States, and Nova Scotia respectively. Both Fabian and Juan were the worst hurricanes to hit their respective areas, causing $450 million in damages and 16 fatalities. Hurricane Isabel was the strongest, deadliest, and costliest storm of the season. Isabel peaked as a Category 5 hurricane over the open waters of the Atlantic; however, it weakened to a Category 2 before impacting the east coast of the United States, causing $3.6 billion in damages and 51 fatalities.

This timeline documents tropical cyclone formations, strengthening, weakening, landfalls, extratropical transitions, and dissipations during the season. It includes information that was not released throughout the season, meaning that data from post-storm reviews by the National Hurricane Center, such as a storm that was not initially warned upon, has been included.

The time stamp for each event is first stated using Coordinated Universal Time (UTC), the 24-hour clock where 00:00 = midnight UTC. The NHC uses both UTC and the time zone where the center of the tropical cyclone is currently located. The time zones utilized (east to west) prior to 2020 were: Atlantic, Eastern, and Central. In this timeline, the respective area time is included in parentheses. Additionally, figures for maximum sustained winds and position estimates are rounded to the nearest 5 units (miles, or kilometers), following National Hurricane Center practice. Direct wind observations are rounded to the nearest whole number. Atmospheric pressures are listed to the nearest millibar and nearest hundredth of an inch of mercury.