[5] The National Weather Service in Los Angeles and Oxnard issued a red flag warning beginning 6:00 p.m. on September 6 through 10:00 p.m. the following day.

The warning highlighted the potential for large wildfires to spread rapidly upon ignition:[6] Strong high pressure will bring a dangerous heat wave and low humidities to Southwest California through at least Labor Day.

Containment difficulties were exacerbated by very dry vegetation and rugged topography that made it difficult to access.

[20] In the San Gabriel Mountains, several types of wildlife and aquatic creatures such as fish, frogs and western pond turtles face extinction as a result of the fires.

Several weeks later, Southern California Edison filed a supplementary letter, stating that tree branches may have come into contact with the utility's power lines and begun the fire.

United States Forest Service investigators took items from the scene into custody, including a section of the conductor line, power poles, and several tree branches.

[24][25] The Forest Service ultimately concluded that a tree had touched the power lines, catching ablaze and starting the Bobcat Fire.