In the right conditions, a small flame can grow into a massive wildfire that threatens homes, wildlife, and entire communities. So, how do wildfires start?
Wildfires can begin naturally or through human activity, but weather often determines how quickly they spread. From strong winds to long dry seasons, nature plays a powerful role in fire behavior. In this article, you will learn what causes wildfires, how many are started by people, and which environmental factors make them worse.
- What Causes Wildfires?
- What Percentage Of Wildfires Are Caused By Humans?
- Factors That Increase Wildfire Risk And Spread
What Causes Wildfires?
Wildfires can ignite from both natural causes and human activities. Regardless of the ignition source, fires need three things to burn: fuel, oxygen, and heat. When these elements come together, especially in dry and windy conditions, a single ignition can start a large fire. Wildfire seasons used to be five months, but the USDA says it’s now over seven months due in part to climate change.
Natural Wildfire Causes
The most common natural causes of wildfires include:
- Lightning strikes, which can hit dry grass, trees, or brush and smolder before catching fire. Hot lightning causes the most natural wildfires because it lasts longer than cold lightning, even though it has less voltage.
- Volcanic activity, where hot lava or ash ignites nearby vegetation.
- Spontaneous combustion, often occurs from piles of decaying leaves or organic matter in extreme heat.
- Drought and wind, which dry out vegetation and allow fires to spread quickly.
Human Wildfire Causes
Around the world, humans are responsible for the majority of wildfires. Common human causes of forest fires include:
- Unattended campfires left burning or smoldering.
- Burning debris on windy days.
- Downed power lines sparking in dry conditions.
- Arson
- Accidental ignition from fireworks, vehicles, or machinery.
- Badly discarded cigarettes
Learn about other natural hazards in our guide to different types of natural disasters.
What Percentage Of Wildfires Are Caused By Humans?
What is the main cause of wildfires? According to the Wildland Fire Management Information (WFMI) and U.S. Forest Service Research Data Archive, about 85% of wildfires are caused by humans. About 29% of human-made wildfires are the result of debris burning. These fires are often preventable and result from carelessness or lack of awareness.
Common triggers include burning yard waste, operating equipment that sparks, and leaving campfires unattended. The remaining 15% of wildfires are caused by natural events such as lightning, but these tend to occur in more remote regions.
By recognizing the most common causes of wildfires, individuals and communities can take simple steps to reduce risk, from monitoring fire restrictions to creating defensible space around homes.
Learn more about staying safe by reading how to prepare for severe weather.
Factors That Increase Wildfire Risk And Spread
Even a small flame can grow into a dangerous wildfire when environmental conditions are right. Key factors that increase wildfire risk and spread include:
- High temperatures: Heat dries out plants and trees, making them more flammable.
- Low humidity: Dry air helps fire ignite and move quickly.
- Strong winds: Gusts carry embers over long distances, starting new fires.
- Prolonged drought: Extended dry periods create fuel-rich conditions that feed fires.
Modern weather technology is helping organizations act before wildfire threats grow. With TempestOne, local utility co-ops and energy providers can build networks of connected weather systems to track real-time wind, temperature, and humidity conditions across their service areas. This data empowers crews to identify high-risk zones, adjust operations to avoid grid failures, and minimise utility wildfire ignitions and maximize operational safety for teams wildfire season.
Explore more prevention strategies in our guide on how to prevent wildfires.
Get Accurate Wind And Weather Readings With The Tempest Weather System
Wildfires often start small but can spread rapidly depending on the terrain and weather. Having accurate, local data can make all the difference.
The Tempest Weather System uses Nearcast™ Technology to deliver real-time updates on wind, humidity, and temperature directly from your backyard. Its AI-powered forecasting helps homeowners and outdoor enthusiasts track changes that could increase fire risk. Whether you live in a fire-prone area or simply want to stay informed, Tempest provides hyperlocal insights you can trust.
Stay prepared and confident in changing weather conditions by shopping for the Tempest Home Weather System!