Tropical storm-force winds affected much of the state as Iselle moved through, except Niihau, the rest of the Hawaiian islands all reporting gusts over . Hurricane-force winds were confined to Mauna Kea on the Big Island, where a peak gust of was observed. Heavy rains affected most of the southern islands, with some areas of the Big Island seeing more than due to orographic lift from the southerly flow on the backside of Iselle. The greatest total was at the Hakalau Forest National Wildlife Refuge, where was observed. Areas on the leeward side of the island saw substantially less rain; Kona International Airport received only during the storm's passage. Kauai saw rains in excess of in several areas and a maximum of at a United States Geological Survey station along the Kilohana Ridge. Totals peaked at to the north on Oahu, while Molokai and Lanai received generally negligible totals. Swells from hurricanes Iselle and Julio also produced waves along the eastern shores of the Hawaiian islands.