The blaze was only 12 percent contained Sunday since April 6 when a lightning bolt ignited it at the Okefenokee National Wildlife Refuge, fire officials said.
More than 130,000 acres are scorched by the fire, InciWeb fire information shows
High temperatures and low humidity fed the flames over the weekend, but the fire's activity is expected to decrease.
Authorities ordered a mandatory evacuation for all St. George's residents on Sunday after the fire spread out of Okefenokee over the weekend.
All schools in St George and Charlton County are closed Monday, school officials said.
"First responders are NOT coming door to door because they are fighting this approaching fire to try to save your homes," said Bruce Young, director of the Charlton County Emergency Management in a message.
At least 75 homes were initially evacuated in the three-mile perimeter around St. George, a town with about 2,000 residents on the border with Florida.
Some residents refused to leave their homes as they could hear helicopters and fire crews battling the fire in the vicinity of their homes.
"It's my home. I want to protect my home and my neighbors. That's just the way I am," St. George resident Marvin Roberts told CNN affiliate WFOX
Smoke and falling ash from the fire reached the Jacksonville, Florida, area, about 30 miles to the southeast.
Some residents in Nassau County, Florida have been put on notice that they may also have to evacuate, the county's emergency officials said.