One more blistering day awaits Bay Area, before cooldown begins

Another blistering hot day was expected to cook the Bay Area on Wednesday, continuing the trend of the past couple of days and creating the possibility that electrical power shutoffs may be coming to the region before it cools down.

Yes, even amid temperatures that are expected to close in on 100 degrees again in the far interior places, the process for a cooldown already was in place, according to the National Weather Service.

“We’re expecting a cooldown to get underway, especially along the coast as the marine layer starts to make its way back,” NWS meteorologist Roger Gass said. “The inland areas will be equally hot as they were Tuesday or close to it, but those areas will start to get cooler as the marine layer builds.”

A heat advisory in place for most of the region Tuesday expired late Tuesday night. The weather service issued a heat advisory on Wednesday only for the Santa Lucia Range and Southern Salinas Valley. It was set to start at 10 a.m. and run through 10 p.m.

On Wednesday, the region’s hottest temperatures are expected to stay below 100 degrees while rising into the high 90s. On Tuesday, the heat did not set any records, the weather service said, but temperatures in several cities broke the century mark. The hottest spot was Byron in the far interior East Bay at 106 degrees.

The gauge also reached 104 in Cloverdale, 102 in Concord, 102 in Livermore and 101 at Lake Berryessa, according to the weather service. The southern Santa Clara Valley also reached 100, the weather service said.

Wednesday’s high temperatures are expected to be mixed with off-shore winds, though the weather service said they don’t expect them to be dangerous ones. Still, PG&E warned that it may implement a public safety power shutoff on Wednesday or Thursday. The utility in a press conference Tuesday said it was monitoring areas in Contra Costa, Alameda, Marin and Monterey counties for potential shutdowns.

The utility had not announced any shutoffs Wednesday morning. Winds are expected to reach gusts of 20-30 mph in areas such as the Altamont Pass, the Pacheco Pass and the Salinas Valley.

“Those will become less and less as we get into Thursday,” Gass said.

As for the cooldown, that process is expected to take a few days, Gass said. Temperatures are not expected to be significantly cooler in the hot spots of the region unti Friday, when the gauge is not expected to rise above the low 80s.

Still, the hottest places Wednesday may feel a bit different than they did on Monday and early Tuesday. Gone is the high humidity. In its place is the dry oven-like heat more common to the area.

The reason: A high-pressure bubble causing a heat wave in much of the western United States shifted east, and monsoonal moisture from the southern desert is no longer bouncing off it and re-circulating around the Bay Area.

“That mugginess was from the upper-level moisture that was moving across the region,” Gass said. “There’s significantly less moisture now.”