What happens to the air quality in various parts of the Bay is still anyone's guess as winds are expected to shift and wildfire smoke from either Mendocino County or the southern Central Valley could move our way. What's for sure is that it's going to be hot — though maybe only warm in SF.
A heatwave moving in this weekend is only expected to bring a high of 76 on Saturday and 80 on Sunday in San Francisco, according to Weather Underground, but when you see forecasts like that at this time of year you can often expect 90 degrees on Potrero Hill and similar hotness in pockets of the Mission.
ABC7 News meteorologist Drew Tuma is forecasting highs of around 100 in the South Bay and East Bay on Monday, with some areas possibly hitting 106 or 107 degrees.
Friday afternoon may see some light smoke blowing down from the north and the ongoing August Complex fire, though a National Weather Service (NWS) model shows that mostly billowing down over Napa County and the East Bay. That big mass of fire to the southeast, however, is the Creek Fire, which remains only 36-percent contained as of Friday morning. That smoke could blow northwest, over us, thanks to a predicted offshore flow this weekend — the potential direction and volume of that smoke still sounds uncertain, per the NWS, but the Chronicle is being much more dire about the situation.
This morning's HRRR smoke model shows a light amount of smoke filtering southward into portions of the North and East Bay over the next several hours.— NWS Bay Area (@NWSBayArea) September 25, 2020
As winds turn offshore and fire conditions become critical late Sat-early Mon, prepare for a potential uptick in smoke. pic.twitter.com/OWR6f9cmaQ
The August Complex remains only 40-percent contained as of today, and the North Complex in Butte and Plumas counties is now 78-percent contained — however it is in the path of what are predicted to be the highest winds on Saturday. The Diablo wind event, according to PG&E, is less likely to impact the North and East Bay hills this time, and therefore a public-safety power shutoff (PSPS) is only being scheduled for parts of Butte, Yuba, and Plumas counties on Saturday.
A Red Flag Warning has nonetheless been issued for the Bay Area beginning at 9 p.m. Saturday, extending through 8 a.m. Monday. Wind gusts of up to 50 miles per hour are predicted at elevations above 1,000 feet, which could make for some dangerous conditions if any fires are sparked.
There is also a High-Surf Advisory in place for much of the Northern California coast, with a buoy off the Monterey County coast recording swells of 15 to 16 feet on Friday. Beach hazard warnings are in effect for San Mateo and Sonoma counties as well.