Wildfire smoke settles into Boise area. Here’s where it’s coming from, how bad it is

Wildfire smoke is settling into the Treasure Valley, but the smog isn’t coming from blazes in Idaho — at least not yet.

The National Weather Service shared a satellite video on social media Monday afternoon that shows smoke sweeping over the Boise area, largely from neighboring Oregon.

“Most of the smoke we’re seeing in the Boise area is coming from the Bootleg Fire in south-central Oregon,” said Spencer Tangen, a meteorologist with the NWS’s Boise office, in a phone interview.

The Bootleg Fire is about 153,000 acres, according to InciWeb, the National Wildlife Coordinating Group’s online fire tracking tool. Another fire — the 90,000-acre Beckwourth Complex in Northern California near the Nevada state line — is also sending smoke toward Southern Idaho, though much of it is settling near Twin Falls, Tangen said.

By Monday afternoon, air quality in the Treasure Valley was in the “moderate,” or yellow category, the second-lowest of six air quality index categories. Air quality in Ketchum and McCall was in the orange category (unhealthy for sensitive groups), while Salmon and Lewiston were in the red category (unhealthy), according to the Idaho Department of Environmental Quality.

The poorer air north of Boise is due to roughly a dozen fires burning in North and Central Idaho, trapping smoke in other Idaho valleys. Tangen said northwest winds picking up Monday evening will blow some of the Idaho fires’ smoke into Boise, worsening the Treasure Valley’s air quality.

“We’re expecting conditions tonight into tomorrow morning to get worse,” Tangen said, though DEQ forecasts show Boise should remain in the yellow AQI category or drift occasionally into the orange.

Tangen said so far much of the smoke around Boise has been higher in the atmosphere, where it doesn’t affect humans as much. Instead, the smoke’s cloud cover has helped temper some of the ongoing high temperatures that have affected Idaho over the last two weeks.

“The smoke’s kind of holding the temperatures down a little bit,” Tangen said.

Monday evening’s northwest winds will likely push smoke closer to the Earth’s surface, meaning smoke could cause more irritation for eyes and lungs.

It’s not yet clear when the smoke could clear up. Tangen said Boise could see a small bit of relief from the ongoing heat, however, as the NWS’s excessive heat advisory expires Monday evening. Forecasts are calling for a high of 98 degrees on Tuesday. Tangen said Boise residents should still avoid outdoor activities in the heat.