The fire began near a Los Angeles Department of Water and Power (LADWP) facility in San Francisquito Canyon near Drinkwater Reservoir.

[2] Overnight, between June 1 and June 2, the fire encountered an area where terrain aligned with high winds, causing it rapidly expand from 5,500 acres (2,200 ha) to 19,500 acres (7,900 ha).

[6] The fire never posed a threat to urban areas because the majority of the blaze was located in Angeles National Forest.

The Powerhouse Fire did pose a threat to local forests as well as to powerlines, watershed areas, and the habitats of threatened and endangered species.

[3] A U.S. Forest Service investigation concluded that the fire had begun when an LADWP power line tripped, based in part on firefighters' discovery of a damaged insulator with signs of arcing at the site of the fire's ignition.