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: