The number of large wildfires has nearly doubled since the 1980s, and the average length of wildfire season has grown by more than two months.
Research shows that changes in climate, especially earlier snowmelt and warming in the spring and summer , have helped boost this increase in fire activity in parts of the West. For much of the West, projections show that an average annual temperature increase of 1 °C would increase the median burned area per year. The increase could be as much as 600 percent  in some types of forests
Wildfire risk depends on a number of factors, including temperature, soil moisture, and the presence trees, shrubs and other potential fuel. All these factors have strong direct or indirect ties to climate variability and climate change. Warmer temperatures and drier conditions can often help increase the chances of a fire starting, or help a burning fire spread. Such conditions also contribute to the spread of the mountain pine beetle  and other insects that can weaken or kill trees, building up the fuels in a forest. Although our choices regarding land use and firefighting tactics can also play a role in lowering or raising risks, observed and anticipated changes in climate have and are expected to increase the area affected by wildfires in the United States.
Since 2000, nine forest fires in the U.S. have caused at least $1 billion in damages each, mainly from the loss of homes and infrastructure, along with firefighting costs.
Damage to homes and other buildings can be substantial, in part from the recent and rapid development of areas near fire-prone forests. As the number of homes located near forests at risk of wildfire has increased over the past two decades, U.S. Forest Service fire suppression expenditures more than doubled between 1991-2000 and 2001-2010 . State wildfire expenditures also increased substantially. While more buildings add to the risk of damage from natural fires, the presence of people in wildlands increases the risk of fires starting. From 2001 through 2011, 85 percent of wildfires were started by people .
Beyond direct damage to the landscape, several public health risks are related to wildfires. Smoke reduces air quality and can cause eye and respiratory illness. Wildfires can also hasten ecosystem changes and release large amounts of CO2 into the atmosphere—contributing to further climate change.
Communities, builders, homeowners and forest managers can reduce the likelihood and impacts of wildfires by: