As of Thursday night, the fire has burned 21,336 acres and was 10 percent contained. Fire officials say lightning probably started the fire in the Holly Shelter Game Land last weekend.
Residents of about 40 homes are being advised to evacuate in an area north of Holly Ridge and along the west side of U.S. 17 into Pender County. An emergency shelter was opened at Southwest Middle School.
People living in coastal communities, including Topsail and Hampstead, were urged to be ready for possible evacuation warnings.
Smoke from the fire has become dense and reached up to 19,000 feet in the atmosphere, Pender County Emergency Management Director Tom Collins said.
Southwesterly winds will likely push smoke over northeastern Pender County and up the East Coast as far as Maryland and Delaware on Thursday night, he said.
The smoke could affect visibility on Interstate 40 and N.C. highways 17, 210, 24, 50 and 53, as well as secondary roads. Near the fire, visibility could drop to as low as 66 feet.
Collins said that road closures are unlikely, but motorists need to use caution.
Air quality has been reduced by the smoke along the North Carolina coast. On Thursday, warnings ranged from the medium-level Code Orange to the most severe Code Purple.
In general, adults and children, particularly those with respiratory conditions, should limit their outdoor activities.