 In mid @-@ September , a tropical low detached from a cold front and developed into Tropical Depression Four late on September 17 , while located about 340 miles ( 550 km ) east @-@ northeast of Bermuda . Early on the following day , the depression intensified into Tropical Storm Bonnie . Due to light vertical wind shear , Bonnie quickly strengthened , and became a hurricane late on September 18 . Further deepening occurred , and at 1800 UTC on September 21 , Bonnie peaked as a 110 mph ( 175 km / h ) Category 2 hurricane . Thereafter , Bonnie became nearly stationary for almost 24 hours . Satellite images indicated that the low @-@ level center became exposed , indicating that Bonnie was significantly weakening while tracking southward . It is estimated that Bonnie weakened to a tropical storm by late on September 24 . Bonnie further deteriorated to tropical depression status on September 26 , but re @-@ strengthened to a tropical storm later that day . 
