A light storm system sweeping through Northern California could lead to a slight respite from drought conditions in the North Bay on Monday, according to the National Weather Service.
Rain, if it comes, is not expected to exceed a tenth of an inch in Sonoma and Marin counties, with a smaller chance of showers along the San Francisco peninsula. Oakland may see some moist fog in the early evening hours to start the week.
Even if the rain is light, the moisture — along with a deepening marine layer across the Bay — should help clear out some of the smoke from wildfires in nearby regions, a National Weather Service meteorologist said.
“It won’t be a lot, but the good news is it will help us avoid critical wildfire conditions,” said meteorologist Brook Bingaman in an interview.
Overall, the Bay Area continues to be see historically low rainfall. The current water year, which runs between the start of October in one year to the next, has seen 37-41% of average rainfall across San Jose, Oakland and San Francisco. Extreme drought conditions have persisted across the state.
— NWS Bay Area (@NWSBayArea) September 25, 2021
Winds from the south have pushed smoky air from wildfires into the Bay Area all week, prompting officials to extend an existing air quality advisory for the region to Monday.
But greyish or even discolored skies aren’t a sign that residents will breathe in smoke this weekend, a spokesman for the Bay Area Air Quality Management District said in an interview.
“The smoke is high aloft, so there’s no danger of poor air quality down at the surface level,” spokesman Ralph Borrmann said. “People will see the polluted skies … but things will change quite a bit to start the week, and we may not extend the advisory beyond Tuesday.”
Tomorrow, 9/25, Air Quality Advisory for Smoke! Bay Area air quality is expected to be Good in the Eastern Zone and the South Central Bay, Moderate in all other regions.
— Bay Area Air Quality (@AirDistrict) September 24, 2021
For the rest of the weekend, the air quality is expected to be good in Contra Costa County and the inland portions of Alameda County, as well as the South Bay.
On the other hand, the North Bay and San Francisco peninsula areas will see moderate air quality, with an average index hovering in the low 50s, just our of the “good” level, according to the air quality district.
Temperatures across the Bay are expected to be mostly the same through Sunday. Inland cities such as Concord and Livermore will remain in the 80-degree range, with San Jose in the mid-to-upper 70s and Oakland in the mid-to-upper 60s.
The light storm system coming through the region to start next week may create a cooling trend that lasts several days and sinks average temperatures by about 5-to-10 degrees across the region.
“Each day will be a little cooler than the day before, and then we’ll start warming up again just a touch on Wednesday,” Bingaman said.
Winds will remain at average speeds through the weekend, but rainy conditions on Monday may bring strong gusts. The North Bay is expected to see surface winds reach 15-25 miles per hour, and surrounding mountain areas could get stronger winds up to 35 mph.