Watch Live Images as - California wildfire advances as heat wave blankets US West.

As firefighters sweltered in 100-degree conditions, the conflagration, which was barely 8% contained, grew dramatically to 86 square miles (222 square kilometers). As a high-pressure zone blanketed the region, it was one of several threatening houses throughout Western states that were anticipated to suffer triple-digit heat into the weekend. Strong winds pushed a wildfire in southern Oregon to 120 square miles (311 square kilometers) Saturday as it raced through dense forest in the Fremont-Winema National Forest near Sprague River, Klamath County. The National Weather Service cautioned that the extreme conditions could result in heat-related illnesses and that California's electrical supply could be disrupted.