Dirty air, dangerous fire conditions bring Bay Area reminders of how August weather can be
On the penultimate day of the month, nature reminded the Bay Area of how August has normally felt and smelled over the past few years, while offering the region a reminder of the danger that usually comes with it.
Amid a Spare the Air alert, air quality pollution figures soared around the region, and the National Weather Service issued its first Red Flag warning in more than a year. Temperatures were expected to creep into the 100s in the Bay Area’s hottest places and move well into the 90s throughout the region.
Additionally, PG&E began a public safety power shutdown to conserve energy that was expected to affect approximately 8,400 customers in small portions of Napa, Colusa, Glenn, Lake, Shasta, Tehama, Yolo and Butte counties. The Pit River Tribes and Grindstone Rancheria also were expected to be affected, according to the utility.
Par for the course, normally, in many previous August months. Not so much in 2023.
“That kind of speaks to the broader scale patterns,” NWS meteorologist Brian Garcia said of the milder weather pattern. “It’s been different.”
The air quality early Wednesday proved to be different than it has most of the summer. According to PurpleAir, a real-time air-quality measuring service, the fine particulate matter rose slightly above 150 in areas of central Contra Costa County and above 100 throughout the East Bay. Anything above 150 means the air quality is unhealthy for all groups. Anything between 101-150 means those with sensitive lungs may struggle.
Closer to the water, the air-quality index ran between 50 and 100, meaning the air was moderately healthy.
Still, dirty air has proven to be more of a rarity. The Bay Area Air Quality Management has issued five Spare the Air alerts in 2023. They issued nine in 2022, 16 in 2021 and 52 in 2020.
The extreme fire danger also has not reared its head as often. The weather service issued its first red flag warning for dangerous fire conditions since October 2021. The warning covered the North Bay interior mountains, especially eastern Napa County and went into effect at 11 p.m. Tuesday. It was set to expire at 8 p.m. Wednesday.
As for the heat, Labor Day weekend temperatures were expected to stay in the 80s in the hottest parts of the region at least through Sunday, with the chance of cracking 90 on Monday. That’s far different than a year ago, when the Bay Area approached the weekend in anticipation of a blistering heat wave that eventually took some record-breaking temperatures past 115 degrees on the holiday.
“We’ve been stuck with a quasi-stationary area of a low trough pretty much all this summer,” Garcia said. “Rather than an inflated high-pressure bubble sticking over us and keeping us hot, we’ve sat there with a weak system off the coast, and keeping the flow from the ocean onto land. That’s kept the heat very moderate.”
The winds were expected to be moderate to heavy in areas of the North Bay. The weather service said Mount Saint Helena felt wind gusts of 43 mph early Wednesday, and sustainable breezes of 25-30 mph were forecast in the areas where PG&E scheduled its power outages.
All of it should begin to calm down Thursday, Garcia said. Cooler air sent from the off-shore trough will bring cooler temperatures and cleaner air by Friday, and even cooler temperatures and easy-to-breathe air on Saturday.