Forecast models run by the National Weather Service showed Friday afternoon that smoke from multiple California wildfires burning in the northwest corner of the state, including the McFarland, Monument and River Complex fires, will linger over the San Francisco Bay Area through the Labor Day weekend.
While the smoke impact isn’t expected to be extreme, the prior models run on Thursday showed the smoke likely clearing over the weekend.
“We’re not seeing enough of an onshore push to completely clear out everything,” weather service meteorologist Roger Gass said of an incoming ocean breeze that won’t be strong enough to clear the smoke.
The Bay Area Quality Management District extended an air quality advisory in effect Friday through Monday.
An air quality advisory is less severe than a Spare the Air alert, which signals unhealthy air quality levels and bans wood burning.
Air quality conditions through Monday are expected to generally be in the “moderate” range on the Air Quality Index, which operates on a scale from 0 to 500. “Moderate” air quality falls between 51 and 100, while “unhealthy for sensitive groups” is in the 101 to 150 range, and “unhealthy” 151 to 200.
On Friday, air quality across the region was mostly “moderate,” with some spots “good.”
“We’re not seeing a significant amount at this point,” Gass said. “Earlier in the day it looked like some was trapped in the atmosphere. There’s still a little haze around. I would say we’re seeing some smoke at about 4,000 to 5,000 feet lingering over the region.”
On Saturday afternoon, the smoke conditions are expected to improve with a light ocean breeze picking up. More smoke is likely to push into the area Sunday and Monday.
The sooty air will be mostly aloft higher in the atmosphere, and while skies may be hazy, air quality levels are not expected to reach unhealthy levels and exceed federal health standards for prolonged periods of time.
This forecast could also change as wildfire smoke movement is tricky to forecast and the slightest wind can move a mass of sooty air from one place to another in minutes.
The smoke will linger as the region is expected to warm up, due to high pressure building over southeastern California.
In the greater San Francisco Bay Area, the hottest days are expected to be Sunday and Monday, with inland locations and higher elevations in the 90s and the hottest interior spots reaching 102 to 108.
The eastern part of Napa County and far East Bay could reach the low 100s, said Eleanor Dhuyvetter, a meteorologist with the weather service.
Coastal areas are forecast to remain cooler and hover between the upper 60s to mid-70s.