FAST FACTS

HOW DID WE GET HERE?

Heavy snows last winter brought relief from a long, brutal drought across much of the West and produced a lush growth of natural grasses—thicker and taller than many vegetation experts had ever seen. But the weather turned very hot very fast in the spring, and the snow melted much faster than expected.

All the grass that grew high dried out, and so did forests at higher elevations, leaving plenty of fuel for wildfires, said Bryan Henry, a manager at the National Interagency Fire Center, which coordinates wildfire-fighting.

Summer lightning storms then dumped less rain than usual and weather conditions kept the humidity low, creating a natural tinderbox in many states.

“It was kind of a bad combination of things,” Henry said.

HOW BIG ARE THE FIRES?

By Thursday, more than 76 large fires were burning in nine Western states—including 21 in Montana and 18 in Oregon, according to the interagency fire center.

So far this year, wildfires have burned more than 12,500 square miles nationwide. In the past decade, only two years were worse at this point in the wildfire season: 2015 and 2012.

For all of 2015, a record

15,800 square miles burned. In

2012, 14,600 square miles were scorched.

WHAT ABOUT CLIMATE CHANGE?

It’s making things worse for fires, said Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan.

Hotter and drier weather is a symptom of human-caused climate change, and that’s making fires worse by leaving forests and other vegetation more flammable.

“It’s not of course playing the only role,” he said. “There’s natural variability at work.”

“Humans are contributing to an ever-increasing degree to wildfires in the West as they emit greenhouse gases and warm the planet and warm the West,” Overpeck said.