Record heat. Extensive drought. "Unprecedented" wildfire conditions. By all accounts, this wildfire season could have been a disastrous one for Idaho.
By late September, about 1,200 fires had burned roughly 429,000 acres of land in Idaho during 2021 — 170,000 acres less than the average acreage burned yearly in the last decade, according to burn totals from the Boise-based National Interagency Fire Center. It's the third year in a row of relatively mild fire seasons in Idaho, in stark contrast to record-setting seasons in much of the West. Meanwhile, state officials said they were challenged by a massive increase in burns on their jurisdiction and were hamstrung by a lack of resources.
What kept the early-summer predictions of catastrophe from materializing? Experts say it was likely a combination of well-timed weather, possible mitigation from wildfire smoke and just plain old luck.
Amid moderate fire season, Idaho department struggled
The 2021 fire "season" is not yet over — officials now measure in fire years as climate change has stretched burn conditions across much of the year. But wet weather and cool temperatures have arrived in Idaho, lowering the risk of new burns and aiding firefighters in corralling the handful that remain.
The 429,000 acres burned this year outpace burn totals for 2020 and 2019 (314,352 and 284,026 acres, respectively) but still fall below NIFC's 10-year-average of 601,825 acres. It's also far below the modern state record of 1,980,552 acres, set in 2007.
For the Idaho Department of Lands, though, it was an outlier year complicated by a lack of resources. The agency heads up fire suppression efforts on state lands, as well as private forests and rangelands. In the previous two fire years combined, the agency reported fewer than 8,500 acres burned. To date in 2021, it estimates nearly 142,000 acres in its jurisdiction have burned. (The National Interagency Fire Center reported about 136,000 acres of burned state land in its year-to-date total. Jessica Gardetto, a spokesperson for NIFC, said state and federal agency tally acres burned differently. In years past, the discrepancy has been as little as a few dozen acres and as much as tens of thousands.)
Josh Harvey, Fire Management Bureau chief for the Department of Lands, said in a phone interview that the 142,000 acres burned this year is 573% of the agency's 20-year-average (about 20,000 acres). The department has spent $71.3 million on fire suppression this year, $5.9 million of which will be reimbursed by the federal government.
"If August had turned out the way forecasters expected it, could've been $90-100 million," Harvey said. "Every metric we were looking at going into summer indicated a record-setting year."
The Department of Lands felt the strain this fire season, not just because of the uptick in burns on its jurisdiction but because of worker and supply shortages.
"I've been in fire about 24 years and I've just never seen the lack of resources that we had," Harvey said.
Harvey said the department was competing with other agencies for hand crews, hotshot teams and even engines. Widespread drought and supply chain issues also meant sourcing water for firefighting and fuel for helicopters and airplanes was "a major struggle," he said.
A cold front that moved across the region in early August helped stretch those scant resources, Harvey said. Moji Sadegh, an assistant professor of civil engineering at Boise State University, said that rare monsoonal weather pattern proved critical in Idaho.
Rare summer storm, widespread smoke helped avert fires
A single storm on July 31 dropped record rain in the Boise area after two months of extreme heat and a parched spring. The same system cooled much of the state and brought much-needed precipitation.
"Usually monsoons don't make it all the way up north to Idaho," Sadegh said. "This time we were lucky to get one major precipitation event midsummer. That helped increase fuel moisture a little bit and helped decrease fire activity."
Paradoxically, the unusually dry spring in the state may also have proved beneficial. Typically, Sadegh said, grasses and shrubs are most dangerous after a wet spring, which causes significant growth, is followed by a hot, dry summer that dries out the new vegetation. Idaho had an unusually dry spring, which could have meant less fuel to burn later.
A mid-August cold front brought unseasonably cool temperatures that also tempered the fire season. Fall settled into much of Southern Idaho with a late September storm that dropped snow at some mountain elevations, effectively cutting off the fire season in some parts of the state.
According to Sadegh, wildfire smoke — much of it from other Western states — may have also played a role in mitigating fire activity in Idaho. The Gem State spent much of the summer inundated with smoke from blazes in California and Oregon. Sadegh said wildfire smoke has been shown to reduce the amount of solar radiation that reaches the ground, lowering ground temperatures. Smoke particles also could disrupt the formation of some types of clouds, including thunderclouds, Sadegh said. Fewer clouds producing lightning strikes — one of the primary fire ignition causes in Idaho — could mean fewer fires.
Sadegh said a major factor in Idaho's milder fire seasons has been a simple one: luck.
"Fire is random," he said. "It depends on many variables converging."
Sadegh said Idahoans shouldn't look at the last few fire seasons as an indicator for the future.
"It doesn't mean we won't have (a major fire) later on or that next year is the same," Sadegh said. "That storm might come, and if the fuel is dry enough, then we might have a very destructive fire."
