What Causes a Wildfire to “Explode?”

On Saturday, weather broadcasters repeatedly referred to a wildfire near Yosemite National Park in California as having “exploded” overnight, going from 10 acres to 5,000 in a matter of hours, with zero percent containment.  Which begs the question, what makes a wildfire “explode?”

All it really takes is a spark to start a fire.  A combination of fuel, air and that one small spark of flame – be it from a power pole, a lightning strike, a campfire, an exhaust pipe, or a cigarette butt carelessly tossed from a car window – is the simple formula for a potential catastrophic fire.  Beyond this, a wildfire currently burning can appear to “blow up,” or “explode” in size when the same simple elements that initially started the fire – heat, fuel and air – are suddenly increased exponentially.

At its height, the 2018 Camp Fire, which erupted due to an outdated power pole spark in the small town of Paradise, California, was burning the equivalent of 60 football fields per minute. That fire is the deadliest and most destructive in the state’s history, fueled by vegetation in an area that had received much less than annual expected rainfall, an extremely hot, dry summer season that lasted into autumn, winds, and of course, that spark from the power pole.

This most recent “Oak Fire” outside of Yosemite, in Mariposa County, California, added sudden strong winds to the mix of 100+ temps and drought dry brush on Saturday, which was enough to make this small brush fire into one that had consumed over 6,000 acres as of Saturday morning, 12,000 as of Saturday evening, over 14,000 as of Sunday morning, and is currently raging out of control.  As of Sunday, Governor Gavin Newsom had already declared a state of emergency for the area, and 3,000 people have been evacuated from their homes.

In the early history of the Earth, nearly all wildfires were started by lightning strikes. Now that humans have come on the scene, we’re responsible for the vast majority of fires.  About 84 percent of wildfires in the USA are started by people, according to a comprehensive study in 2017 published in the Proceedings of the National Academy of Sciences. And then there’s increasing drought conditions, which, according to all the climate scientists, is caused by Climate Change, which is mostly a crisis caused by human activities on the planet.

According to the June 2022 Drought Report published by the NOAA’s National Center for Environmental Information, the current drought conditions for the southwestern United States that have been brewing for the last five years and now bled further into the central and southern states, have moved past “severe,” and are now considered “extreme” for more than 34% of the country.

All it takes is a spark. So be aware, be responsible, and don’t make one.


Photo Credit: Toa55 / Shutterstock.com