California has dry, windy, and often hot weather conditions from late Spring through Autumn that can produce moderate to devastating wildfires. At times, these wildfires are fanned or made worse from strong, dry winds, known as Diablo winds in the northern part of the state and Santa Ana Winds to the south. Wildfires in California are growing more dangerous and costly. U.S. taxpayers are paying about $3 billion a year to fight wildfires, triple what it cost in the 1990s, and big fires can lead to billions of dollars in property losses.
In some parts of California, fires can sometimes recur in areas that have had past histories of fires. Examples of this are in Oakland, which fires of various size and ignition occurred in 1923, 1931, 1933, 1937, 1946, 1955, 1960, 1961, 1968, 1970, 1980, 1990, 1991 , 1995, 2002, and 2008. Other examples being Orange County, Riverside County, San Bernardino County, and Los Angeles County. In the case of Orange and San Bernardino, these two counties share a county border that runs north to south through the Chino Hills State Park, with the parks landscape ranging from large green Coastal sage scrub, Grassland, and Woodland, to areas of brown sparsely dense vegetation made drier by droughts or hot summers. The valley's grass and barren land can become easily susceptible to dry spells and drought, therefor making it a prime spot for brush fires and Conflagration, which many have occurred since 1914. Hills and canyons that have seen brush or wildfires in one or similar locations have occurred in 1914, the 1920s, 1930s, 1940s, 1950s, 1960s, 1970s, 1980s, 1990s, 2000s, and into today.
On occasion, freak lighting strikes from Thunderstorms may also inadvertently spark wildfires in areas that have seen past ignition.