No injuries or structure damage has been reported.
Swartley warned that forecast temperatures near 100 degrees this weekend keep conditions ripe for the blaze, Swartley said. "When the fire comes near, the vegetation is that much more ignitable because they are already warm," Swartley said.
Gov. Mike Easley has declared a state of emergency in three counties. He warned that driving could be difficult with smoke-filled roads, but officials said none were expected to be closed.
For the past few days, smoke from the fire has blown north into heavily populated areas along Virginia's coast. But the winds have shifted, and forecasters expect the smoke to blow east toward the Outer Banks on Saturday.
Fire officials told residents that smoke from the blaze could linger in the area for months because the fire may smolder in the decayed vegetation that makes up the peat-filled soil. Peat is flammable, and over millions of years turns into coal, Swartley said.
"You won't see open flame. The ground is just really hot - you can't walk on it," Swartley said.
The only way to stop the fire from burning in the soil is to flood it. Firefighters are pumping water from nearby Phelps Lake to extinguish the ground fire in some areas. However, the only thing that will put all of it out for good would be several inches of rain at one time, like from a tropical storm, Swartley said.
The fire was sparked by lightning a week ago.
In California, a wildfire that briefly threatened 50 homes in the mountains northwest of Los Angeles pass was contained early Saturday. The blaze in the Grapevine area along Interstate 5 in the Tehachapi Mountains had charred about 500 acres - less than a square mile - of grass and brush by the time it was declared surrounded.
Residents of about 50 homes in Digier Canyon were advised to leave but the threat ended and the fire basically had stopped growing by Friday evening.
Damp weather during the night helped keep the fire down.
The cause of that fire had not been determined.