The eye of the nearly 300-mile-wide storm, blamed for at least four deaths in Samoa last week, was nearing Nadi, the Australian Broadcasting Corp. reported.
"The cyclone is currently very close to Nadi, probably just to the west, so Nadi itself is probably under what's called the eye wall of the cyclone. The winds are very strong, it's raining very heavily," said Peter Kreft, chief forecaster at the Meteorological Service of New Zealand.
Wind gusts of up to 168 mph were reported.
More than 3,000 people moved to evacuation centers as the Category 4 storm bore down on the nation, the government said.
The Information Ministry said a hurricane warning was posted for the Yasawa and Mamanuca island group and wind warnings were issued for the entire nation of about 870,000 people ahead of the storm.
In Suva, roads were closed due to fallen trees, the ministry said. Telecommunications throughout the country were disrupted. High winds ripped apart houses and other buildings.
Fiji Meteorological Service meteorologist Sanjay Prakesh said conditions were worsening across the country, with the northeastern part "already experiencing the effect of the cyclone."
ABC said all flights in and out of Fiji were canceled, but the international airport at Nadi was crowded with people who had been evacuated from resorts.
Resort manager Gordon Leewar told ABC his guests decided to wait out the cyclone at his northern Fiji resort.
"We have five couples on our property at the moment and they're really happy to stay," Leewar said. "We've asked them whether they want to be evacuated, but they've said, 'No, we want to stay and we hope for the best.'"