Wildfire smoke continues to make air quality poor across wide swaths of Northern California, including the Sacramento region.
There’s no relief in sight the next few days, weather officials say.
The air is unhealthy and the sun has been slow to peek through Thursday near the capital, but it is indeed smoke, not clouds, turning the sky gray. Local air districts at SpareTheAir.com showed multiple air quality index readings just above the threshold of AQI 150 that’s considered “unhealthy”: Downtown Sacramento was at 153, Davis at 159 and Elk Grove at 162 as of 11 a.m.
Smoke continues to exude from the now 56,000-acre Glass Fire, which is burning actively just east of Santa Rosa in the North Bay region with only 5% containment, Cal Fire said Thursday. Onshore winds from the Bay Area carried smoke east, directly toward Sacramento, earlier this week.
But also still of concern for the capital region and much of the rest of the Sacramento Valley are two other, massive wildfires that have each been burning since mid-August farther north in the state.
At the northwest edge of the valley, the August Complex centered around Mendocino National Forest is approaching 1 million acres, by far California’s largest wildfire in history. The blaze is reportedly 51% contained, still growing in some of its zones and producing plenty of smoke. And northeast of Sacramento in the foothills, the North Complex near Plumas National Forest continues to billow smoke from its North Zone and East Zone, though its deadly West Zone is now almost fully contained with no fire activity.
Fires continue to burn “east of us, northeast of us and northwest of us, so if we get winds blowing from any of those directions … (smoke) would likely blow toward Sacramento,” weather service meteorologist Scott Rowe said.
Recent smoke forecasts posted by the the weather service’s Sacramento and Bay Area offices show the unfortunate scenario expected for Northern California’s most populous regions over at least the next 48 hours.
Sustained winds of up to 20 mph and gusts of 30 mph at higher elevations are expected through at least the start of the weekend, according to both weather service projections. Those winds, which have prompted a red flag warning for the North Bay from 1 p.m. Thursday to 6 a.m. Saturday, are forecast to be westerly or northwesterly, meaning they’ll blow west-to-east or northwest-to-southeast.
That will take the bulk of the Glass Fire’s smoke straight into the East Bay and likely the South Bay starting Thursday afternoon.
Then, starting around Thursday night and lasting into early Friday, heavy amounts of smoke are expected to roll south from the August Complex. The shifting northwesterly winds could then take that blob of polluted air down through most of both the Sacramento Valley and the Bay Area, throughout Friday and possibly beyond.
Rowe says that in terms of incoming wildfire smoke based on the current conditions, any relief the wind might provide for Sacramento this weekend would be very temporary.
“We could switch to more onshore flow, which could help us for a brief amount of time over the weekend,” Rowe said, but with the Glass Fire still actively burning in the North Bay, “onshore winds would just blow that (smoke) over to Sacramento.”
Fire from the North Complex is predicted to drift east, potentially toward Chico in Butte County.
Beyond the weekend, wind outlook is still unsettled. Rowe emphasized that smoke forecasts from the weather service are “experimental” and the weather service doesn’t forecast AQI levels. And neither weather service nor air districts can account for the possibility of new fire starts, or predict to what extent gusty winds might flare up smoke output from existing ones, further worsening air quality.
Another byproduct of the smoke coverage is that it has the potential to keep temperatures across Northern California cooler than the record-threatening highs expected Thursday and Friday, blocking out sunlight on what’s supposed to be a significantly hotter than average day.
That’s also hard to predict, and will depend on when and where exactly the smoke coverage ends up being the thickest. Smoke cool-down happened in Sacramento at least once this summer. Aug. 20 was forecast a day in advance to exceed 100 degrees at Sacramento Executive Airport, but the high ultimately hit just 88 degrees as the sun never broke through. Downtown Sacramento was a few degrees warmer, but still only in the 90s.
And a decent amount of smoke this Wednesday wasn’t enough to stop Sacramento from soaring to a record-breaking 102 degrees, breaking the Sept. 30 record of 101 degrees set in 1991.
Rowe said highs in Sacramento are expected to reach about 101 degrees Thursday and Friday in Sacramento, which would match and be 1 degree shy of those dates’ all-time records, respectively, for downtown.
The currently elevated AQI levels are from particulate matter (PM 2.5) pollution, fine particles that are one of the most hazardous types of air pollutant and most closely associated with wildfire smoke.
When AQI levels reach unhealthy levels, people should avoid outdoor activities as much as possible. A general rule of thumb is that if you can smell wildfire smoke while outside, that means it could be harmful to your health, regardless of the precise AQI reading.
Climate change and California wildfires
Wildfires have always been part of life in California. The past four years have brought some of the most destructive and deadliest wildfires in the state’s modern history.
Nearly 180 people have lost their lives since 2017. More than 41,000 structures have been destroyed and nearly 7 million acres have burned – that’s roughly the size of Massachusetts.
So far this year, 30 people have died, according to Cal Fire.
Meanwhile, this year’s August was the hottest on record in California. A rare series of lightning storms sparked a series of fires, including the August Complex that has burned roughly 840,000 acres, making it the largest wildfire in California’s recorded history.
Our climate is becoming more severe.
The 2017 wildfire season occurred during the second hottest year on record in California and included a devastating string of fires in October that killed 44 people and destroyed nearly 9,000 buildings in Napa, Lake, Sonoma, Mendocino, Butte and Solano counties.
The following year was the most destructive and deadliest for wildfires in the state’s history. It included the Camp Fire, which destroyed the town of Paradise and killed 85 people, and the enormous Mendocino Complex.