GRANTS PASS, Ore. (AP) – Favorable weather conditions allowed firefighters to make substantial progress in containing a blaze in southwestern Oregon.

The Oregon Department of Forestry says Wednesday that a fire adjacent to the Interstate 5 highway is now 25% contained.

Fire managers are working to contain as much of the fire as possible before the weekend is expected to bring hotter and drier weather conditions. The department says crews have so far been able to prevent 4.7 square miles (12 square kilometers) of timberland from burning.

Oregon’s Milepost 97 fire is believed to have started Wednesday because of an illegal campfire.

The fire has burned over 18 square miles (46 square kilometers) in rugged terrain between Roseburg and Grants Pass.