 The hurricane continued to move west @-@ northwest through its duration , and reached its peak strength of 120 mph ( 190 km / h ) on July 25 . Iselle crossed Socorro Island , which recorded a 70 mph ( 110 km / h ) sustained wind and heavy rain on July 25 . The hurricane weakened on following days after it moved over cooler waters , downgraded to a tropical storm on July 28 and subsequently into a tropical depression on July 30 . The depression dissipated later that day , after losing its low @-@ level circulation <unk> mi ( <unk> km ) southwest of San Diego . 
