Wildfire is a naturally occurring phenomenon with some experts describing it as Mother Nature’s method of housekeeping, i.e., a way to dispose of dead brush, branches, limbs and logs. Wildfire is also a way for fire-dependent species to reproduce and survive. However, wildfire is also caused by human behavior; in these situations often homes are lost or damaged. Wildfires occur around the globe, but certain ingredients such as fuel (vegetation) type, humidity, weather trends and topography make some geographic areas more fire-prone than others. For example, an area with large sections of dry or dead vegetation, or areas with large amounts of resinous plants such as conifers (pines, spruces, etc.), brush, chaparral, or palmetto cause that area to more likely experience a wildfire.
Frequency of Wildfire
The frequency and the intensity of wildfires vary due to fuels, climate and topography. While a state such as Michigan will experience around 8,000 wildfires per year with most under 100 acres in size, other states such as California, will experience tens of thousands of wildfires per year, but most will be under 100 acres in size. We remember the wildfires where many homes are destroyed. The 1991 Oakland Hills fire, where almost 3,000 structures were destroyed covered about 1,500 acres. The 2003 Cedar fire in Southern California burned 275,000 acres and destroyed about 2,400 structures. Often, wildfires occur during specific seasons. For example, in the Great Lakes area, spring is the predominant wildfire season due to extensive fine fuels (grass, leaves) that are left after the snow melts. Couple this with the traditional yard clean-up, including raking and burning, and we see why wildfires are a problem at this time. However, in other states, late spring through fall are the predominant seasons. However, being weather-dependent, wildfires can occur at any time, in any state, depending on conditions.
The cause of wildfires also varies. For instance, in Western states and Florida, up to half of all wildfires are caused by lightning, whereas in the Great Lake States, only around 5 percent are caused by lightning unless there has been an extended drought. In those cases 100 percent of lightning strikes can result in a wildfire.
Other causes of wildfire include carelessness in burning debris, ATV exhaust, equipment fires, campfires, fireworks, downed power lines, arson, children playing with matches, other human activities such as smoking, and even trains.
Slope, hills, valleys, canyons, and mountains have an important effect on wildfire. Wildfire will intensify as it climbs a slope due to “pre-heating” of the fuels immediately up-slope. Canyons and chimneys can funnel winds and the wildfire uphill, creating even more intensity. Some areas are known for high winds, such as in southern California where the Santa Anna winds are well known to increase wildfire intensity. Homes built on these slopes or at the top of ridges are in the direct path of wildfire. This not only means the homes are in the most vulnerable location, but also adds to the problem of evacuation should a wildfire occur.