Extreme heat wave expected to hit Bay Area over Labor Day weekend

The Bay Area could experience its highest temperatures of the year over the Labor Day weekend, with triple-digit readings across the region as a high pressure ridge that originated at the Four Corners continues to build over Nevada and into California.

The conditions have prompted the National Weather Service to issue excessive heat warnings for all of the Bay Area and the Central Coast beginning Saturday and extending through Monday.

The weather patterns will create “on-shore winds that compress the marine layer to the point where the marine layer really doesn’t exist,” NWS meteorologist Braden Murdock said. “Once that happens, the thermometer just goes up and up.”

And up, and up, and up.

“It’s gonna be the hottest heat wave of the year, and the most widespread,” Murdock said. “It’s not just a run-of-the-mill one.”

Temperatures in the inland East Bay and areas of the South Bay are expected to start rising Wednesday, with high temperatures of 97 degrees expected in Brentwood — the hottest spot in Contra Costa County — as well as 92 in Concord and 90 in Walnut Creek. Livermore is expected to be Alameda County’s hottest place at 92. Morgan Hill is also expected to reach 90 degrees, while San Jose will see temperatures as high as 88.

Those temperatures, as well as others through the non-coastal areas of the region, are expected to increase by 5-8 degrees Thursday as the marine layer begins to dissipate and winds change direction and move toward the ocean. The heat wave is forecast to peak Monday, with temperatures forecast at 110 degrees in Brentwood, and at least 104 degrees in Concord, Walnut Creek, Dublin Pleasanton, Morgan Hill and Hollister.

Even typically cooler areas, like Oakland and San Francisco, will see temperatures in the upper 70s and 80s. And to the south, the thermometer could reach 115 degrees in parts of the Los Angeles Basin and the Inland Empire.

The air quality in the Bay Area is expected to be moderately healthy, according to a forecast by the Bay Area Air Quality Management District. Moderately healthy air would bring air-quality index readings between 51-100.

The heat comes as the calendar winds down on what forecasters have called a pretty mild summer. The region has seen some heat blips but nothing that has lasted so long with such hot temperatures.

“We’ve been very fortunate,” Murdock said. “Sometimes, we see events like this in the spring and summer. But the pattern this summer hasn’t been particularly dynamic, and we’ve seen most of the extremes to the north (in Oregon and Washington). Of course, this is the time of year where we can see this pattern set it a bit more often. In that sense, it’s not that unusual.”

Climate scientist and weather expert Daniel Swain wrote on social media that the heat wave may be “prolonged, dangerous and almost certainly record-breaking.”

I’ll have a Weather West update on this upcoming severe heatwave later today. Looking increasingly like a prolonged, dangerous, and almost certainly record-breaking heat event. Monthly Sep records now probable and some all-time records possible in Sacramento Valley.#CAwx #CAheat https://t.co/esX6SKHAot

— Daniel Swain (@Weather_West) August 30, 2022

Cooling centers were expected to be available for people in Santa Clara, Contra Costa and Alameda counties. Fire crews will change some of their regular patterns to cope with the heat.

“We’ve made some adjustments to make sure that the crews get their duties done early in the morning, so they’re not in the sun unnecessarily,” Livermore-Pleasanton Fire Deputy Chief Jason Solak said.

In Contra Costa County, fire officials have made staffing and strategic adjustments, so that additional ambulance drivers and paramedics are available, along with more fire crews.