The Madre fire burning in the mountains above Azusa will probably not be fully contained until Oct. 2, authorities said Tuesday.
The blaze was only 5% contained Tuesday morning and had burned through 200 acres of brush and other fuel as crews tried to gain the upper hand.
An aerial assault was underway Tuesday morning.
The number of personnel battling the blaze also tripled to 450 from Monday to Tuesday and firefighters were hoping that low winds -- churning at about 10 miles per hour -- and higher relative humidity of 19% would help their efforts, according to the U.S. Forest Service.
"That's not too bad," U.S. Forest Service spokesman Shaun Rollman said of the wind. And he added that "the humidity's in double digits, so that's a good thing."
The fire started Monday at about 6 p.m. in San Gabriel Canyon north of Highway 39.