Hurricane Isabel produced winds and storm surges that caused extensive damage in several Mid-Atlantic states. It was the first hurricane to affect the region since 1999. A predominant pattern with an upper level trough over the northeastern portion of North America produced westerly flow aloft during the previous three hurricane seasons and much of 2003. The upper level pattern caused tropical cyclones to recurve northeastward before they reached the coast. As hurricane Isabel approached the coast an upper level ridge built northeast of the storm and the resulting upper level flow interacted with the storm and resulted in landfall on the coast of North Carolina.

When Ignacio reached hurricane strength over the eastern North Pacific on 24 August 2003, it became the first hurricane of the season. This event marks the latest date for the initial formation of a hurricane over the eastern North Pacific in the record. While there has been much prior work on the spatial and temporal distribution of tropical cyclones, the circumstances surrounding hurricanes Isabel and Ignacio suggest the need for a further examination of the frequency of these storms. This research examines the spatial and temporal distribution of the frequency of tropical cyclones over the Atlantic and eastern North Pacific oceans. A statistical analysis is performed to determine if any significant shift in the temporal distribution of tropical cyclones throughout the season has occurred. Comparative analyses for the Atlantic and eastern North Pacific basins are examined for the years 1964-2003. An attempt is made to link the results of that analysis to other large-scale climatological patterns.