The 2018 wildfire season was the deadliest and most destructive wildfire season on record in California, with a total of 8,527 fires burning an area of 1,893,913 acres (766,439 ha), the largest area of burned acreage recorded in a fire season, according to the California Department of Forestry and Fire Protection (Cal Fire) and the National Interagency Fire Center (NIFC), as of December 21.

The Mendocino Complex Fire was the largest recorded fire complex in California history. It was a large complex of two wildfires, the River Fire and Ranch Fire, which burned in Mendocino, Lake, Colusa, and Glenn Counties in the U.S. State of California, with the Ranch Fire being California's single-largest recorded wildfire.

The fires collectively destroyed 280 structures while damaging 37 others; causing at least $267 million (2018 USD) in damages, including $56 million in insured property damage and $201 million (2018 USD) in fire suppression costs.