The storm located is about 1,335 miles east-southeast of Hilo, Hawaii.
Douglas is forecast to remain a major hurricane over the next several days as it moves across the Pacific, but will weaken near Hawaii as it heads into cooler waters east of the islands.
Hawaii will need to keep an eye on the storm from Sunday into Monday.
As it moves through the Central Pacific, Douglas is a Category 3 storm, which means it has sustained winds between 111 and 129 mph.
Hurricanes reaching Category 3 and higher are considered "major hurricanes" because of their potential for significant loss of life and damage.
Eric Blake, a senior hurricane scientist at the NHC, said that Douglas is "putting on quite a show" over the Pacific.
"The Hawaiian Islands need to watch this one," he tweeted.
The Hawaiian Islands may see strong winds and flash flooding as the storm passes over the island chain late Saturday night. Hurricane-force winds extend outward up to 30 miles from the center of the storm, while tropical-storm-force winds extend outward up to 90 miles.
Any part of the state could be affected, but it remains too early to know its precise path.
John Bravender, National Weather Service warning coordination meteorologist, advised residents to have hurricane kits ready, get gas, and make sure their houses are ready to withstand the storm.
“These are the things we want to do ahead of time so that once a hurricane like Douglas approaches you’re not scrambling,” he told KHON2.
Local officials are already preparing for impacts in the state.
In Honolulu, city and county officials said they are expecting flooding and are making plans to install storm drain inlet protection devices on city streets to minimize ponding and flooding in nearby areas, KHON2 reported.
Federal forecasters said in May that the Central Pacific basin, including Hawaii, should expect to see between two and six tropical storms or hurricanes this year.
Hurricane season in Hawaii lasts from June 1 until the end of November. August and September are historically active months for cyclones in the region.
Last year, four tropical cyclones developed in the Central Pacific. None directly impacted Hawaii.
In 2018, the massive and powerful Hurricane Lane made a last-minute turn and narrowly spared Oahu, Hawaii's most populous island. The last major hurricane to strike the state was Hurricane Iniki in 1992, which hit Kauai and caused massive damage across the island.
The Associated Press contributed to this report.