The last large wildfire in Los Angeles County (burning 4,000 acres or more) was the Route Fire, ignited Oct. 31, 2022, along Interstate 5 near Castaic, burning more than 5,200 acres. The last significant wildfire in Los Angeles County, the Bobcat Fire, burned an area nearly as large as the San Fernando Valley in Los Angeles. The wildfire, having burned from September 6, 2020, through late October, ranked as the second largest in the history of Los Angeles County wildfires and tenth most destructive. It burned 115,796 acres (mostly within the Angeles National Forest) and destroyed 170 structures, including 87 residences.
Source: InciWeb - Incident Information System and Angeles National Forest.