This NOAA image shows Hurricane Lane on August 21, 2018 as headed toward the Hawaiian islands, where hurricane warnings and watches have been issue

Residents of Hawaii on Wednesday braced for a powerful hurricane bearing down on the US state, with warnings issued in several counties in the island chain.

President Donald Trump, in a tweet, urged residents to prepare for Hurricane Lane, which is expected to bring torrential rains, high winds and dangerous surf.

"Everyone in the path of #HurricaneLane please prepare yourselves, heed the advice of State and local officials, and follow @NWSHonolulu for updates. Be safe!," he said.

Lane weakened slightly overnight to a Category 4 storm, packing maximum sustained winds of 155 miles per hour, the Central Pacific Hurricane Center said.

The National Weather Service said a has been issued for Maui County and Hawaii County while a hurricane watch was in effect in Kauai and Oahu.

"The center of Lane will move very close to or over the main Hawaiian Islands from Thursday through Saturday," it said.

It added that though Lane is forecast to weaken in the next 48 hours it will remain a dangerous hurricane as it nears the Hawaiian Islands.

"Lane is expected to produce total rain accumulations of 10 to 15 inches with isolated amounts greater than 20 inches over the Hawaiian Islands," the NWS said.

Map showing the trajectory of Hurricane Lane, which had reached the maximum Category 5 designation as it headed toward Hawaii

Hurricanes rarely make landfall in Hawaii and the last major storm to strike the island was nearly three decades ago, when Hurricane Iniki barrelled into the island of Kauai, leaving six people dead and $3 billion in damages.

In preparation for Hurricane Lane, state officials have closed schools and public offices in the counties affected while residents rushed to stores to stock up on water and food.

Governor David Ige on Tuesday declared a state of emergency on the Big Island to help provide relief for damage from the hurricane.

"Hurricane Lane is not a well-behaved hurricane," he said in a statement. "I've not seen such dramatic changes in the forecast track as I've seen with this storm.

"I urge our residents and visitors to take this threat seriously and prepare for a significant impact."

© 2018 AFP