The Atlantic season's fourth tropical storm, dubbed Dorian, formed Wednesday, but did not present any danger on land, the National Hurricane Center in Miami said.
The center of the storm lay 410 miles (660 kilometers) to the west-southwest of the Cape Verde archipelago, off the coast of West Africa, with maximum sustained winds of 50 miles (85 kilometers) an hour.
According to the NHC, the storm was moving rapidly across the Atlantic Ocean at a speed of 21 miles per hour.
Dorian could strengthen slightly in the coming hours, but, by Thursday, experts predicted it would weaken as it moved over cooler water.
Meteorologists from the National Oceanic and Atmospheric Administration warned in May this year's hurricane season would be more active than usual.
They predicted the formation of 13 to 20 named tropical storms and six to 11 hurricanes -- including three to six major ones, with winds stronger than 110 miles per hour.
The hurricane season lasts from June 1 to November 30.