Fire crews and emergency service vehicles from Natrona County were responding about 9 p.m. to three blazes on Casper Mountain.
Crews were setting up an incident command post at the parking lot at the Hogadon Ski Area.
The largest fire was visible from Casper and was in a steep area near the west side of the mountain.
The other, smaller fires were on Muddy Mountain and Jackson Canyon.
One year ago this week, the Jackson Canyon fire spread across the western third of Casper Mountain. The fire burned in an area of about 12,000 acres.
The cause of the fires was unknown, although a brief thunderstorm had moved through Natrona County earlier this evening.
By 9:30 p.m., the Natrona County Sheriff's Office had closed Micro Road.