Fires

Idaho just had its most mild wildfire season in years. What caused it?

After years of massive blazes, devastating wildfire damage and smoky air, Idahoans breathed a little easier this summer. But don’t expect that to last, experts say.

Across the West, this summer’s wildfire season has been what University of Idaho climatologist John Abatzoglou called “a welcome reprieve” from recent record-setting fire years when more than 10 million acres have burned nationwide each year, according to the National Interagency Fire Center. In contrast, nearly 4,350,000 had burned nationwide by Sept. 19 of this year.

“This is the quietest season I’ve had in five years here,” said Eric Fransted, assistant fire management officer for the Idaho Bureau of Land Management. “We do assist national efforts, but nationally it was a pretty quiet fire season, too.”

Fransted said some firefighters who’ve been in the area longer likened this year to wildfire seasons from the mid-1990s.

By Sept. 19, 516 fires had burned 280,032 acres in Idaho. That’s about half of the average acreage for the last five years, Fransted said. It’s also half the normal number of fires.

Perhaps most noticeably, the Treasure Valley experienced the best summertime air quality in five years because of the decrease in fires across the region. From June 1 to Sept. 15, the Idaho Department of Environmental Quality tracked 88 days of “good” air quality and 19 days of “moderate” air quality. Air quality never dipped into “unhealthy” categories during that time, unlike in previous years when the DEQ has deemed air quality unhealthy as many as 20 times in the same time period.

What caused mild Idaho fire season?

At the start of the fire season, experts predicted an unusually wet spring in the Treasure Valley could mean one of two things: a more mild fire season due to the precipitation or an unusually intense one thanks to the increased fuel load.

Abatzoglou, who studies the impacts of weather and climate change in the region, said several factors contributed to the season.

“Statewide, temperatures were the coolest they’ve been since 2011,” Abatzoglou said in a phone interview, though he said temperatures were still a degree warmer than the 20th Century average.

“We actually had a dry summer,” he added. “It was dry and cool, which is a curious combination. And we avoided any prolonged hot spells.”

Those long stretches of scorching days can cause fire fuels to dry rapidly. Triple-digit temperature days were fewer and farther between this year, Abatzoglou said.

“The weather conditions just weren’t quite there,” said Fransted, the BLM fire expert. “We didn’t get quite as much lightning. But the fuels were there. The potential was there.”

Fransted said there also seemed to be fewer human-ignited fires. He hopes that’s a sign that people were more careful with fires.

The lower number of ignitions also contributed to a snowball effect.

“In years when we have really extensive areas burned, it’s usually when we have multiple ignitions at once,” retired U of I fire ecology professor Penny Morgan said. “When lots of fires burn at once, it’s harder to suppress fires when they’re still small.”

With fewer fires to chase, Fransted said, firefighters had the resources to catch the fires quickly.

2020 wildfire forecasts

Abatzoglou said there’s often one year of lag between rainy years and intense fire seasons — meaning 2020 could bring more blazes to Idaho thanks to the plentiful grasses and growth this year. Fortunately, Abatzoglou said, some fires this year were allowed to burn because of the lower-risk conditions. That helped naturally clear fuel loads.

“One way to try to curb the negative impacts of fire is to take advantage of years like this year,” he said. “But years like this are going to be fewer and farther between.”

Fransted said his team used the downtime this summer for additional training, prescribed burns and fuel reduction work, but it’s far too soon to know how that will influence next year’s wildfire season.

Though wildfires this year didn’t live up to predictions of more devastating fire seasons in the future, Abatzoglou said those forecasts still hold true.

“We have seen more intense fires for the last 50 years,” he said. “We certainly expect to see years like this year, even with the changing climate. But we’re essentially loading the dice for fuels that lend themselves to more active fire seasons.”

Morgan said intense fires are an inevitability as warming trends continue.

“The outline is for longer, drier fire seasons, and we’re already seeing that,” she said. “The question is not if but when the areas we care about will burn.”

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Nicole Blanchard is the Idaho Statesman’s outdoors reporter. She grew up in Idaho, graduated from Idaho State University and Northwestern University and frequents the trails around Boise as much as she can.
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