How Do Most Wildfires Start?

As Smokey Bear says: "Only you can prevent forest fires." But even with that admonition, 84 percent of all wildfires in the United States are still started by people. A 2017 University of Colorado study of 1.5 million wildfires that flared up between 1992 and 2012 also found that humans have added three months to the length of the average national fire season. “Thanks to people, the wildfire season is almost year-round,” said study lead author Jennifer Balch. The annual cost of fighting all those wildfires in America has exceeded $2 billion USD in recent years.

How and when wildfires start:

• The remaining 16 percent of wildfires start naturally, usually after lightning strikes.
• The most prevalent day for human-ignited fires is the Fourth of July. The University of Colorado study counted 7,762 total wildfires on Independence Day during those 21 years.
• Of the human-started fires with a known cause, burning debris caused 29 percent, arson was responsible for 21 percent, equipment use was blamed for 11 percent, campfires were the source of 5 percent, and children caused the remaining 5 percent.