People living in the Red Top Meadows subdivision, from the school bus turnaround north and from South Fall Creek Road east, are advised to be ready to evacuate.
The Rock Creek fire, burning on the west side of Munger Mountain in the Bridger-Teton National Forest, was first reported around 4:30 p.m. Saturday.
The fire is about a half mile south of Red Top Meadows.
Crews are working to put out the 5-acre fire, using two helicopters, three engines and one water tender.
There are no road or trail closures in the area, but caution is advised.
The cause of the fire is under investigation.