Honolulu (CNN) -- As the first light of dawn broke Friday in Hawaii, officials reported no significant damage from a series of tsunami waves that struck the islands after Japan's deadly earthquake.
The tsunami brought waves of about 6 feet to a harbor in Maui, authorities said, but other areas reported lower levels, including Honolulu at 2.2 feet and Hilo at 4.3.
The U.S. mainland, meanwhile, was bracing for waves to come onshore, from Washington to California.
No significant damage had been reported in Hawaii almost three hours after the first waves arrived, but officials said they would know more after sunrise and then make a decision on whether evacuees could return to their homes.
Sensors on the southern side of the island of Hawaii, sometimes called the "Big Island," were wet, indicating ocean water had come at least 100 feet ashore, officials said.
CNN affiliate Hawaii News Now broadcast images of fish that washed up by the tsunami on Maui.
Kerry Gershaneck of the Pearl Harbor Naval Shipyard told Hawaii News Now that the operation planned to open once officials gave the "all clear."
Businessman Charlie Leonard, who lives on the 19th floor of a condo on Waikiki Beach in Honolulu, said Hawaiians took this tsunami more seriously than they did last year following an earthquake in Chile.
"It came home to people," he said, referring to the devastation in Japan. "I think everybody's grateful" that damage does not appear to be major.
Honolulu is about 6,859 miles (11,038 kilometers) from the location of the February 2010 Chile earthquake. Sendai, Japan -- located near the epicenter of Friday's quake -- is 3,782 miles (6,086 kilometers) away.
Leonard and a business partner operate a waste and recycling business and had to move about 50 trucks late Thursday.
The Pacific Tsunami Warning Center predicted the waves, which came in about every 15 minutes, "are not going to be a major damaging event" for Hawaii, but will cause scattered damage, particularly to harbors and coastal facilities.
It appeared the state's residents had heeded calls to move away from the coast. Honolulu officials told residents to "be aware that inundation effects could continue for several hours."
"We called this one right," center geophysicist Gerard Fryer said. "This evacuation was necessary."
Waves of between 6 and 7 feet were reported at Kahului harbor in Maui, Fryer said, adding that it was difficult to tell what would happen on all the islands. "We have significant energy bouncing around the Hawaiian Islands."
Fryer said the waves are rolling in about 15 minutes apart. Forecasters said some areas may see waves of up to 9 feet.
A tsunami warning was still in effect after 8 a.m. (11 a.m. ET).
Communities along much of the U.S. West Coast were under tsunami warnings, too.
The National Weather Service said the waves would hit Oregon and California.
In California, tsunami wave heights could reach 7 feet at Port San Luis Harbor and 4 feet in Morro Bay. Santa Monica could see 2.8 feet.
San Francisco Mayor Ed Lee says he feels "confident we will not be hurt by this."
He expected the city to get waves 1 to 2 feet higher than normal. Extra precautions have been taken in case the situation worsens, but he said he has not had reason to call for evacuations.
"I ask the public to remain calm," Lee said.
He said he will be calling Japan's consul-general in San Francisco to offer any assistance to that country.
The first impact in Hawaii was felt shortly after 3:07 a.m. (8:07 a.m. ET), according to Hawaii State Civil Defense, which issued a tsunami warning.
Tidal gauge readings on the southern side of the Hawaiian island of Kauai were "somewhat encouraging," CNN meteorologist Rob Marciano said.
Hawaii Public Radio news director Bill Dorman told CNN some roads were closed as a precaution.
Hawaiian emergency officials reminded residents that tsunami evacuation maps can be found in front of their telephone directories.
Chief Petty Officer Kurt Fredrickson in Honolulu told CNN the U.S. Coast Guard has been working with local port authorities and harbor masters to get the word to all mariners to get out to sea.
The Coast Guard prepared for the worst-case scenario, Frederickson said. "We are moving our assets out to sea. We are moving our aircraft to more suitable locations."
The threat of a tsunami prompted the U.S. National Weather Service to issue a warning for at least 50 countries or territories around the Pacific after the 8.9-magnitude earthquake struck Japan on Friday. The warning for Guam was later lifted.
Warnings also were in effect for coastal areas of California and Oregon from Point Concepcion, California, to the Oregon-Washington border, according to the U.S. Pacific Tsunami Warning Center. An advisory was in effect for Washington.
A warning also was in effect for Alaska, from Amchitka Pass to Attu, and in Canada's British Columbia.
President Barack Obama said he instructed the Federal Emergency Management Agency to be prepared to help Hawaii and other U.S. regions "that could be affected" by the disaster.
CNN iReporter Ken Papagno, who lives on the Hawaiian island of Oahu, recorded sirens that sounded throughout the island.
Hawaii had a tsunami scare in February 2010 after an 8.9-magnitude earthquake hit Chile. A warning cancellation occurred nearly two hours after the first waves came ashore. Coast Guard crews said they had found no significant damage to ports or waterways as a result of the tsunami, ending a significant evacuation to higher ground.