Following the passage of Gustav, no damage or fatalities were reported. The ninth tropical depression of the season developed from a tropical wave 700 mi (1,125 km) west-southwest of Cape Verde on August 25. The depression headed west-northwestward, while slowly intensifying and establishing better-defined upper-level outflow. By August 26, the depression intensified enough to be upgraded to Tropical Storm Hortense. After becoming a tropical storm, Hortense was steered nearly due north, under the influence on an upper-level low. Hortense later headed generally northwestward, after the upper-level low degenerated into a trough and moved eastward. Although intensification was somewhat slow, Hortense managed to peak as a 65 mph (100 km/h) tropical storm on August 28. On August 29, nearby Hurricane Gustav was rapidly intensifying, and began to significantly affect Hortense with increasing vertical wind shear. Hortense weakened, with the storm degenerating into a tropical depression on August 30. Further weakening occurred, and Hortense dissipated on August 31 roughly east-southeast of Bermuda. A vigorous tropical wave exited the west coast of Africa on September 3. It quickly developed an area of deep convection with a well-defined circulation, which prompted it being classified a tropical depression on September 4. At the time it was situated hundreds of miles south of Cape Verde at a very southerly latitude of 7.2°N, making it the southernmost-forming tropical cyclone on record in the north Atlantic basin. Initial intensification was slow as the system moved northwestward, a movement caused by a large mid-level trough over the central Atlantic. On September 5 the NHC upgraded the depression to Tropical Storm Isidore. Subsequently, it intensified at a faster rate, becoming a hurricane on September 6. The following day, satellite estimates from the Dvorak technique suggested a peak intensity of 100 mph (165 km/h) and a minimum barometric pressure of 978 mbar (hPa; 28.88 inHg). After peaking, Isidore entered a region of stronger upper-level winds and quickly weakened. By September 8 it had deteriorated into a tropical storm, although re-intensification occurred after the shear decreased. An eye feature redeveloped in the center of the convection, and Isidore re-intensified into a hurricane on September 9. It ultimately reached a secondary peak intensity of 90 mph (150 km/h).