The storm caused very bad damage on the islands of Niihau , Kauai , and Oahu . Some wind gusts reached 100 mph ( 160 km\/h ) , and waves were over 30 feet ( 9 m ) high . The hurricane devastated the islands of Niihau , Kauai , and Oahu with wind gusts exceeding 100 mph ( 160 km\/h ) and rough seas exceeding 30 feet ( 9 m ) in height .