State officials are urging residents and visitors to heed warnings. Forecasters say even if Lane doesn't make landfall, the islands could be walloped with rain and wind.
Gov. David Ige has declared a state of emergency.
"Preparations to protect life and property should be rushed to completion", the service added.
The eastern side of the island picked up almost 3 inches (7.62 centimeters) of rain in three hours, while there was light rain in other areas, Foster said.
While the Big Island, at most immediate risk from Lane, has been hit by tropical depressions and storms, it also has never been struck directly by a hurricane-strength storm in modern records.
Rainfall of 20 inches in some areas could lead to flash flooding
After hitting the Big Island, the storm is expected to churn north over the islands of Maui, Lanai and Moloka'i.
"We can't go in because the roads - there's a river of water down there", said Hawaii County Managing Director Wil Okabe.
He won't be joining them and instead is staying home with his four children since there's no school.
The first emergency shelters are preparing to open as Hurricane Lane heads toward Hawaii.
State offices on Hawaii island and Maui will be closed Wednesday through Friday.
It's possible Oahu and Kauai may later be included in a weather service advisory for the hurricane. All of Hawaii is under a flash flood watch.More news: Swedish election: far right on course for sizeable gains in vote
Many live near beaches and streams that could face flooding.
The U.S. Navy was moving its ships and submarines out of Hawaii.
Rear Adm. Brian Fort, commander of the Naval Surface Group Middle Pacific, said Wednesday that all ships not now undergoing maintenance are being moved.
Navy aircraft will be kept in hangars or flown to other airfields to avoid the storm. The sharper the turn to the north, the more likely one or more islands will endure a direct hit.
The category 4 hurricane is located about 500 miles southeast Hawaii Island and 670 miles southeast of Honolulu. "That being said, on our current forecast, as of the afternoon on Thursday, we still have it as a major hurricane". As of late Tuesday local time, it had sustained winds of near 160 miles per hour, according to Hawaii News Now.
The National Oceanic and Atmospheric administration has been sending multiple aircraft into and around the storm in order to help observe the hurricane and improve the forecast, providing a better idea of the threat Lane presents to Hawaii.More news: North Korea holds military parade without showing ICBMs
The centre of the storm is expected to track "dangerously" close to or over the islands between Thursday and Saturday, the NHC said.
On Tuesday night, the National Weather Service announced that Hurricane Lane had become a Category 5 hurricane. It may take until the weekend for Lane to succumb to wind shear and weaken to a tropical storm. Offshore buoys also had detected wave action associated with the storm. Hurricane force winds extend outward up to 30 miles from the storm's center, and tropical storm force winds extend outward up to 120 miles.
The most powerful storm on record to hit Hawaii was Hurricane Iniki, a Category 4 storm that made landfall on Kauai island on September 11, 1992, according to the National Oceanic and Atmospheric Administration.
"Personnel in Navy Region Hawaii, including on Oahu and Kauai, should follow hurricane awareness and preparedness guidelines established by city/county and state government", the Navy said.More news: Trump aide Papadopoulos gets 14 days in prison