 Part of a tropical wave organized into a tropical depression on July 21 . It headed westward and out to sea , strengthening into a tropical storm the next day . Gilma rapidly strengthened and became a hurricane exactly one day after it was named . It continued to intensify as it entered the central Pacific . Shortly after entering the central Pacific , Gilma reached Category 5 intensity on the Saffir @-@ Simpson Hurricane Scale , the second of the season . It then suddenly weakened for unexplained reasons , and weakened into a tropical storm on July 27 . It became a depression three days after that and dissipated on July 31 . Hurricane Gilma had minor impact on Johnston Atoll . That atoll received light rain , wind gusts to near gale force , and surf . No casualties or damage were reported . 
