Unhealthy air quality is spreading throughout Northern California. How bad will it get?
With mostly uncontained wildfires burning and billowing smoke, air quality is once again deteriorating throughout several large parts of Northern California, which is also facing yet another round of windy conditions and potential record-setting heat to open October.
California’s air quality index levels Wednesday and Thursday are expected to be worst in areas close to the Glass Fire, which is burning in the Napa-Sonoma region commonly called Wine Country.
“Moderate northerly winds will spread wild fire smoke over much of the Sacramento Valley and into the northern San Joaquin Valley today and Thursday,” the National Weather Service’s Sacramento office tweeted Wednesday morning.
AQI readings had already entered “unhealthy” territory in Elk Grove and in parts of Yolo and Solano counties Wednesday morning. The readings continued to climb into the afternoon. Davis, Woodland and Vacaville each had AQI levels above 150 as of 9:30 a.m., according to the local air districts at SpareTheAir.com.
Air quality levels in the Sacramento region Wednesday remained steady, if unhealthy, as the afternoon progressed.
At 2 p.m., UC Davis showed an AQI reading of 164. Elk Grove and Woodland posted 159, but the worst air in the region was in Vacaville, which logged 182 just after 1 p.m.
Air pollution levels were a bit lower closer to Sacramento: AQI reached 135 downtown in the morning. But that was short-lived as AQI in downtown Sacramento leaped to 153 by early afternoon.
AQI readings between 101 and 150 are considered “unhealthy for sensitive groups.” The forecast predicts AQI levels in the unhealthy range near Sacramento through Friday.
Readings were much lower outside of downtown Sacramento, in Placer County where the AQI level in Lincoln was 80, 82 in Auburn and 90 at Roseville’s monitoring station at North Sunrise Avenue and Douglas Boulevard. In rural south Sacramento County, Sloughhouse posted a 76 just after 1 p.m.
Less than two hours later, about 2:30 p.m., Cal Fire crews in neighboring Amador County were tackling the new Copper Fire. Cal Fire officials in a tweet said the 25-acre blaze was burning on Copper Hill Road off of Highway 16 east of Rancho Murieta. The fire moving in a southerly direction at 2:30 p.m., closed Highway 16 between Ione Road and Old Sacramento Road near Plymouth. Mandatory evacuation orders were issued for Long Gate Road near Plymouth as firefighters and air tankers worked to contain the blaze.
According to the latest forecasts from the U.S. Environmental Protection Agency’s AirNow map, air quality in the range considered “unhealthy” for general population, AQI 151 to 200, is expected to continue through at least Wednesday for the East Bay and North Bay areas, extending up north along the coast through much of Mendocino County, before winds shift direction on Thursday.
The NWS Bay Area office has issued a fire weather watch warning for portions of the South Bay and North Bay areas, including the immediate Glass Fire zone. It will be in effect 1 p.m. Thursday through 6 p.m. Friday due to sustained winds coming in from the northwest between 10 mph and 20 mph, with gusts as high as 30 mph at higher elevations.
A NWS fire weather watch is one level below a red flag warning, an alert issued for wildfire weather conditions that are considered “critical.” Red flag warnings were in place Sunday and Monday, when the Glass Fire erupted in size.
Hot start to October in Sacramento
Meanwhile, forecasts show high temperatures in or near triple-digits are expected the next two days across the Sacramento Valley. That includes the capital city, where NWS forecasters currently predict a high of 100 degrees Thursday sandwiched between high-90s temperatures Wednesday and Friday.
Those highs will be about 15 degrees hotter than normal for Sacramento, where Oct. 1 has historically averaged 84 degrees. The all-time record downtown on that date is 101 degrees, set in 2001.
Across the valley and foothills, highs will range from the 90s through low 100s Thursday and Friday, before dipping down to the mid-80s and mid-90s by the weekend.
Also in Sacramento’s daily forecasts through at least Friday: “Widespread haze” from “patchy smoke.”
None of this is unfamiliar territory for the capital region.
California’s wildfire season roared to life in mid-August, caused for the most part by a freakishly powerful thunderstorm that dropped thousands of lightning strikes throughout the north half of the state. That storm came the same weekend as the peak of a historic heat wave in the valley that saw temperatures in Sacramento soar past 110.
The Sacramento area had about a two-week reprieve from poor air quality beginning in mid-September. For about nearly a month before then — especially the days following the major Sept. 8 flare-up on the North Complex burning in Butte and Plumas counties — air quality has ranged from poor to terrible near the capital.
More on state’s wildfires, smoke output
The Glass Fire and the Zogg Fire, just west of Redding in Shasta County, are still going strong. Each were reported by Cal Fire at around 50,000 acres Wednesday morning after sparking Sunday amid extremely gusty red-flag conditions.
California’s largest wildfire ever recorded, the nearly 1 million-acre August Complex, is burning with less than 50% containment at Mendocino National Forest, with its northern edge roughly 30 miles south of the Zogg Fire. And the 314,000-acre North Complex, which sparked at Plumas National Forest mid-August and erupted in early September, is also still producing some smoke locally, though Cal Fire reported Tuesday that its deadly and destructive West Zone is almost fully contained.
The quartet of major fire incidents form a rough triangle: the Glass Fire in the North Bay, the North Complex in the Sierra Nevada foothills, and the August Complex and Zogg Fire on the western edge of the northern Sacramento Valley. The EPA anticipates AQI levels at least in the “unhealthy for sensitive groups” classifications to continue through at least Thursday for the inside of that triangle.
This story was originally published September 30, 2020 at 10:23 AM with the headline "Unhealthy air quality is spreading throughout Northern California. How bad will it get?."
