Hurricane Lala skirted Hawaii’s Big Island without making landfall and is expected to gradually weaken after lashing the region with strong winds and drenching rain that flooded roads and turned rivers into raging torrents.

The possibility the island could witness its first direct hit from a hurricane in 155 years faded as the eye of the storm passed the island’s southern tip. Landfall is not expected at this point, said National Weather Service meteorologist Joseph Clark.

However, hurricane-force winds were expected to continue into overnight (Hawaiian time), with the strongest wind gusts likely in areas of higher terrain, the National Hurricane Centre said. Heavy rainfall into Sunday could produce flooding and mudslides, while powerful waves pound the coast, the agency said.

Tropical storm warnings remain in effect for the islands of Maui, Molokai, Lanai, Kahoolawe, Oahu, Kauai and Niihau as the storm moves west. The Big Island is the state’s largest, with a population of about 210,000.

Whitecap surf slammed ashore nonstop, howling winds whipped the tops of palm trees and waterways swelled with fast-moving run-off from relentless rain that blew nearly sideways.

Governor Josh Green, noting rainfall of five centimetres an hour, said people should be sheltering in place.

Forecasters said higher elevations on the island, dominated by the towering Mauna Kea volcano, could get as much as 63 centimetres of rain. That could cause life-threatening mudslides in a mountainous area where people live off the grid in improvised housing.

Earlier the governor called it an enormous storm capable of destructive flooding and even the possibility of wildfires kicked up by strong winds across the island chain.

Tens of thousands of homes were without power. Hawaiian Electric warned customers to expect “possible extended outages, potentially overnight”, as the storm system made its way westward across Hawaii.

On the Hamakua Coast on the Big Island, utility crews were assessing a 67-kilometre span of transmission lines after fallen trees knocked down poles and structures, Hawaiian Electric told TV station Hawaii News Now.

Bobby Camara, a 75-year-old lifelong resident, said he planned to “hunker down, cross my fingers, hope the lights don’t go out” at a care home just outside the town of Hilo. He said petrol stations were busy as people sought fuel for chainsaws and vehicles.

“I think stocking up is part of life over here ... You learn to be self-reliant,” Camara said.

Mike Caputo, who lives in Keaau, near the Big Island’s east coast, said his power generator was ready and a home water tank was full. He said the main concern was flash flooding and fallen trees, especially albizia, a common tree.

“They’re not very sturdy, but they grow extremely large,” said Caputo, 50, a local fire captain. “They can make roads impassable.”

Lala intensified from a tropical storm into a hurricane on Saturday as its maximum sustained winds increased to 120kmh, the hurricane centre reported, making it a Category 1 hurricane.

A hurricane last made landfall on the islands in 1992, when Hurricane Iniki — a Category 4 storm — lashed Kauai.

“It did $US3 billion worth of damage. It destroyed thousands of homes, and it did kill six people,” said Green, the governor. “We just can never know if a storm is going to turn.”

The Big Island was last hit directly in 1871, when a Category 3 hurricane hit the northeast corner, according to research by a University of Hawaii atmospheric scientist.

On Saturday, shelters were opened, events were cancelled and ranchers were urged to leave their cattle in pastures rather than structures that might collapse.

Christine Matsuda, who lives in Waimea, on the northern side of the island, said large gusts were rattling her whole house every few minutes. “We’re finding unexpected leaks in places that don’t see water under normal conditions,” Matsuda said.

The hurricane centre predicted 20 to 30 centimetres of total rainfall across Maui and the lower elevations of the Big Island, and 10 to 15 centimetres across the island chain.

Many Hawaii residents are still dealing with the aftermath of devastating floods in March.

AP, with Reuters