Forest fires commonly occur in areas that regularly experience dry weather, strong winds and warm temperatures. In the United States, forest fires most frequently occur in western states, such as California, Oregon and Washington, according to National Geographic.
Forest fires, or wildfires, require the presence of fuel, oxygen and heat. Dry vegetation resulting from drought is highly flammable, providing fuel for forest fires. Strong winds replenish oxygen and aid the spread of flames. Warm temperatures stimulate combustion. A spark provides the catalyst for forest fires and may come from a burning cigarette, strike of lightning, or arson, reports National Geographic.