What Causes US Wildfires?
Breakdown of named wildfire causes across the tracked sample: lightning ignitions, human-caused ignitions, and unknown/under-investigation fires.
Nationally, the US Forest Service and NIFC report that roughly 85–90% of wildfires are human-caused (unattended campfires, burning debris, equipment sparks, downed power lines, arson, cigarettes, vehicle exhaust on dry grass). Lightning causes the remaining 10–15% by fire count — but lightning fires tend to burn larger areas because they typically start in remote terrain where response is slow. In big lightning outbreaks like the August 2020 California complex fires, thousands of strikes in a single day can start hundreds of new ignitions simultaneously, overwhelming suppression capacity.
Cause Breakdown (tracked named fires)
| Cause Category | Fire Count | % of Named Fires | Total Acres Burned |
|---|---|---|---|
| Lightning | 0 | 0% | 0 |
| Human | 0 | 0% | 0 |
| Unknown | 0 | 0% | 0 |
| Other | 0 | 0% | 0 |
Sample size: 0 named fires with a recorded cause. National statistics from NIFC and USFS include thousands of small fires not in this sample, where human causes dominate by count.