Triple-digit temperatures coming to Bay Area
Barometric pressure will build. Clouds will mostly clear out. And the temperature gauge likely will climb first into the upper 90s and then into the 100s by Friday in some of the Bay Area's hottest places, according to the National Weather Service.
Yet, this early June heat wave around the region will be far from a typical one.
“This time, the upper-air pressure isn't going to be as strong, and there's going to be a low-pressure flattening out with a trough coming from the Pacific Northwest,” NWS forecaster Matt Mehle said Wednesday. “So this hot spell will be very brief. From Friday to Sunday, there will probably be a drop from 15-20 degrees.”
It may be brief, but it also will be intense, Mehle said. An excessive heat watch has been issued for most of the Bay Area's inland areas beginning at 11 a.m. Friday, and Mehle said it is likely that it will be upgraded to a heat advisory.
The warm-up will begin Thursday, when temperatures in Livermore, Concord and Brentwood — generally three of the hottest spots in the Bay Area's interior region — all are expected to roll past 95 degrees. Cities in the Santa Clara Valley, another of the region's hot spots, are expected to see temperatures in the low 90s.
By Friday, the East Bay's interior region is expected to get as high as 104 degrees, while areas of the Santa Clara Valley, including San Jose, Gilroy, and Morgan Hill are expected to reach at least the mid-90s.
Daniel Swain, a climate scientist, posted on social media that this heat-up could bring with more humidity than usual, as well.
By Saturday, Mehle said the low-pressure trough moving south will mix with the upper-air pressure that's not as strong as usual and that the hot air will be pushed out of the area. By Saturday, temperatures are expected to be in the low 90s in the hottest spots and the 80s elsewhere. On Sunday, even the hottest spots will be lucky to crack 80, he said.
“Some of the long-range models even show some light rain possible way up north,” he said.
Cities along the Peninsula and along the coastline in Alameda County will be spared the heat, he said. Temperatures are expected to peak around 86 degrees in Oakland on Friday, while San Francisco will peak at 77 and Monterey at 73.
“We've still got a little onshore flow,” Mehle said of the sea breeze that is typical for the coastal cities. “That will keep our coast a little tempered.”
The air quality around the Bay Area may be slightly affected, according to the Bay Area Air Quality Management District's forecast. The fine particulate matter was below 50 and considered good on Wednesday, but it could get into the moderate level, between 51-100 by Friday in some areas.