The Madre Fire in eastern San Luis Obispo County continued to grow overnight as firefighters battled challenging conditions at the large blaze.

According to Cal Fire’s Saturday morning incident report, the fire has now burned 79,630 acres. Containment remained at 10%.

Overnight saw several “large areas of perimeter growth and intense fire” at the northwestern and southeastern borders of the blaze, as well as “moderate areas of intense fire” along the northwestern perimeter and isolated fires within the perimeter, the report said.

Cal Fire said the primary fire carrier was “grass and chaparral with an oak hardwood overstory.”

“The area has minimal previous fire history,” the report said. “These fuels are positioned on steep nearly inaccessible terrain with limited access points for ground resources.”

Looking ahead through the weekend, Cal Fire said major concerns are high-voltage transmission lines in the area, threats to the major commerce route of Highway 166, cultural and heritage areas, federal and local communications infrastructure, and cattle grazing land.

Check back with Noozhawk for updates to this story.