Roadblocks have been set up to prevent beach access, and along Waikiki, one of Hawaii's most famous beaches, guests in lower floors of the hotels are being told to move to higher floors.
The National Weather Service has reported that waves at Marquesas Island on the northern edge of French Polynesia, hundreds of miles south of Hawaii, were smaller than forecast, saying in a tweet "Hawaii impact could be less than initial expectations."
Six-foot tsunami waves were reported on some parts of French Polynesia. Those waves are expected to continue their northward motion.
Immediately following the 8.8-magnitude quake off central Chile, 4- to 8-foot waves were reported along the South American coastline.
"What we're looking at is a tsunami that could be two to three meters for some areas in Hawaii," Jenifer Rhoades, Tsunami Program Manager at the National Weather Service, told MSNBC. "That means it could be 6 to 8 feet of inundation in some areas."
The Federal Aviation Administration has closed Hilo International Airport on the low-lying eastern side of Hawaii's Big Island. Honolulu International Airport on Oahu is expected to remain open.
White House press secretary Robert Gibbs said President Obama would be receiving updates during the day in the White House Situation Room.
The president made a statement outside the White House this afternoon, offering his condolences to victims of the Chile quake and assurances that the administration is making preparations for the tsunami.
"We can't control nature, but we can and must be prepared for a disaster if and when it strikes," Obama said.
The Federal Emergency Management Agency says it has "pre-deployed assets" in Hawaii, including food, water, generators and other resources ready to roll out as needed.
In addition to Hawaii, the tsunami warning also affects Guam, American Samoa and coastal areas of California and Alaska. The PTWC forecasts waves of 2 to 3 feet to could surge on the California beaches of La Jolla, Santa Monica, Los Angeles and Morro Bay.
Since a tsunami is a series of waves, emergency management officials are warning people to remain on alert even after the first wave or waves arrive.
"The time from one tsunami wave to the next can be five minutes to an hour," the PTWC bulletin reads. "The threat can continue for many hours as multiple waves arrive."
Residents are advised to remain on high ground until local authorities give the "all clear," which could come no sooner than two hours after the estimated time of the tsunami's arrival.
For ships and animals at sea -- including humpback whales that migrate to the Hawaiian Islands this time of year -- the tsunami poses little threat, experts say. The danger is as the surging waves come into shallow water, and have nowhere to go but up onto shorelines.
Following a 9.5-magnitude quake that struck Chile in 1960, the ensuing tsunami killed more than 200 people, including 61 in Hawaii.
Experts say any tsunami to hit Hawaii this time will likely be much smaller since the quake itself was not as strong.
ABC News' David Herndon, Jake Tapper, Luis Martinez and Nancy Ayala contributed to this report along with The Associated Press and Hawaiian ABC affiliate KITV.