Bay Area air quality advisory extended through Wednesday because of Oak Fire smoke

SAN FRANCISCO -- Drifting smoke from the massive Oak Fire burning near Yosemite will bring hazy skies to the Bay Area over the next few days, prompting air district officials to extend an air quality advisory through Wednesday.

As of 9 a.m. Monday, the Oak Fire had charred 16,791 acres in Mariposa County and was 10 percent contained, according to Cal Fire. 

More than 2,500 fire personnel are fighting the blaze, which was reported on Friday afternoon and exploded in size over the weekend.

Winds are pushing smoke from the wildfire to the Bay Area. An air quality advisory issued for Monday has been extended through Wednesday, according to the Bay Area Air Quality Management District.

Air quality is forecast to be good to moderate for the region and pollutant levels are not expected to exceed the national 24-hour health standard.

A Spare the Air Alert is not in effect, the air district said. Real-time air-quality monitoring is available on the BAAQMD website. The Purple Air website also provides localize air-quality data.

The air advisory triggered confusion for some in the Bay Area who only saw clear blue  skies Monday.  

East Bau residents Aileyn Ecob and Jane Patty have a standing date every Monday morning to walk the Shell Ridge Open Space in Walnut Creek, with one caveat: wildfire smoke. 

"We wouldn't be out here if we could smell it in the air," Patty told KPIX 5.

"I just smell the summer vegetation. The kind of dry summer vegetation. I don't smell anything," said Ecob. 

They were surprised to hear about the air quality advisory from the Bay Area Air Quality Management District about smoke from the Oak Fire some 120 miles away, especially with the marine layer dominating much of the skyline. 

BAAQMD spokesperson Erin DeMerritt said the organization still anticipates Oak Fire smoke to impact the region. 

"We do expect smoke from the Oak Fire to drift into the Bay Area over the next couple of days. The good news is we expect this smoke to stay mostly aloft and not impact the air quality at ground level," she explained, meaning the smoke will stay at elevations of 4,000 feet and higher, near the tops of Mount Diablo, Mount St. Helena and Atlas Peak. 

Brian Garcia, a warning coordination meteorologist with the Bay Area office of the National Weather Service says the reason for bright blue skies and good air quality amidst smoke is wind direction. 

"The winds up higher are blowing from east to west, but everything down low is blowing from west to east. So we're going to keep pushing that out of our area, so we won't get that full column of intense smoke. And the fire outputting smoke would have to increase substantially and blow in our direction," he said. 

A repeat of the infamous orange day on September 9th, 2020 is unlikely. Garcia says that was the perfect confluence of events, starting with intense smoke from the Bear and August Fires in far Northern California and a north wind that parked them in the Bay and into the marine layer, tinting the sky an ominous tangerine shade. 

"I hope we don't get that. That's really terrible when we have an orange sky and can't go outside because it smells so bad. But it's nothing like those folks who have to live in it. I guess we're the lucky ones," Ecob said. 

Garcia says Monday's advisory is a good reminder to prepare for the inevitable wildfire tainted air quality days that are yet to come this summer and fall. 

"Now is the time to prepare. If you need to, go out and purchase an air filtration system. You need to go out and buy some N95 masks."

Andria Borba contributed to this story.