A search-and-rescue operation was launched after flash floods apparently swept several occupied homes off their foundations in the coastal communities of Na'alehu and Wai'ohinu, near the southern tip of the Big Island.

Heavy rainfall sent torrents of water and debris down steep mountainsides, creating dangerous conditions across parts of Hawaii. Some higher-altitude areas of the Big Island received up to 89 cm of rain.

Civil Defense, the National Guard and a Coast Guard helicopter joined the search-and-rescue operation as emergency crews faced rushing water, debris and boulders blocking roads.

Honolulu experienced widespread storm-related damage, with dozens of downed trees, blown roofs and damaged power lines reported by the fire department.

Fewer than 60,000 homes and businesses remained without power by Sunday morning, down sharply from more than 200,000 several hours earlier. At least three hospitals were operating on generator power.

Large waves battered the coastline as Lala passed west of the Big Island. The storm's winds drove rain almost sideways and caused waterways to swell with fast-moving runoff.

Much of Hawaii remained under a flash flood warning, with heavy rain, mudslides, flooding, downed trees and power lines posing major threats to residents.

Wind gusts of more than 161 kph were recorded at higher elevations on Mauna Kea, one of the most powerful wind readings reported as Lala moved across the island chain.

As of 8 am Sunday in Hawaii, Lala was centred about 105 km southwest of Honolulu and moving northwest at around 22 kph. Wind gusts of nearly 112 kph were reported in Kaneohe on Oahu.