wildfire

thumb|upright=1.35|Wildfire burning in the Kaibab National Forest, [[Arizona, United States, in 2020. The Mangum Fire burned more than of forest.]] A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Some natural forest ecosystems depend on wildfire. Modern forest management often engages in prescribed burns to mitigate fire risk and promote natural forest cycles. However, controlled burns can turn into wildfires by mistake.

Wildfires can be classified by cause of ignition, physical properties, combustible material present, and the effect of weather on the fire. Wildfire severity results from a combination of factors such as available fuels, physical setting, and weather. Climatic cycles with wet periods that create substantial fuels, followed by drought and heat, often precede severe wildfires. These cycles have been intensified by climate change, and can be exacerbated by curtailment of mitigation measures (such as budget or equipment funding), or sheer enormity of the event.