Hurricane Hector is now 1,130 miles southeast of Big Island and moving west, according to the NHC's latest advisory.
Maximum sustained winds have increased to near 140 miles per hour (220 km/h) with higher gusts.
The Hawaiian Islands were placed on alert as Hector inched toward the central Pacific with maximum sustained winds of 125 miles per hour.
The Central Pacific Hurricane Center forecasts that Hector will continue to travel toward the WNW at an increased forward speed through Tuesday, followed by a westward motion Tuesday night through Friday. The center of Hector will pass just south of the Big Island by about 150 to 200 miles, close enough to the Big Island to bring enhanced showers and thunderstorms and gusty winds.More news: SpaceX launches Indonesian comsat with 'used' booster
"Interests in the Hawaiian Islands should monitor the progress of Hector", the NHC said. "Now is a good time for everyone in the Hawaiian Islands to ensure that they have their hurricane plan in place", it said.
A powerful hurricane is on course to collide with an erupting volcano on Hawaii's Big Island within days, forecasters have said.
Hurricane Hector updated satellite imagery as of 11 p.m. on Sunday, Aug. 5, 2018.
Forecasters with the National Weather Service say "Hector will cross into the local region from Tuesday night into Thursday, though it remains too early to determine precise impacts on island weather at this time".More news: Britain plans for default opt-in organ donation to save lives
Remember that the forecast track and intensity can and will change.
The current Kilauea lava flow from one of about two dozen volcanic fissures that opened in the ground has been going on for 93 days, making the longest non-stop eruption on record from Kilauea's lower East Rift zone.
Lava spewed from Kilauea since May 3 has covered 13.4 square miles (34.7 sq km) of the island's surface, destroying more than 700 homes and displacing thousands of residents.More news: Serena Williams cites personal reasons for Rogers Cup withdrawal