The Category 4 storm's dangerous center could make landfall this week, but even if it doesn't, it should draw close to the islands Thursday through Saturday, bringing destructive winds and as many as 20 inches of rain onshore, forecasters said.
The state is bracing for a powerful punch: The governor has declared an emergency, and all public and charter schools on the Big Island and Maui County are closed until further notice.
People have been flocking to stores for supplies.
"(I'm) filling up my bathtub with some water, hoping to board up my main windows in time," a shopper on the Big Island, Shana Bartolome, told CNN affiliate KHON on Tuesday.
The storm was in the Pacific about 305 miles south of the Big Island town of Kailua-Kona early Wednesday, with maximum sustained winds of 155 mph.
Lane is expected to weaken slowly through Friday, but it still is forecast "to remain a dangerous hurricane as it draws closer to the Hawaiian Islands," the National Weather Service's Central Pacific Hurricane Center says.
A hurricane warning is in effect for Hawaii and Maui counties -- meaning hurricane conditions are expected there.
A hurricane watch has been issued for Oahu and Kauai. The watch indicates hurricane conditions are possible and that winds of at least 39 mph are anticipated in the next two days.