The Florida Forest Service and St. Lucie County firefighters battled an 80-acre brush fire off Glades Cut-Off Road Monday.
Crews were called out to the Baker Ranch just after noon.
The fire has been contained at 80 acres.
No homes were threatened but the fire was clearly visible from Interstate 95.
Investigators say lightning started the fire.
The Florida Forest Service says smoke will linger Monday night and Tuesday and it urges drivers to use caution.