A warm, sunny start to the week will give way to clouds, cooler temperatures and perhaps a speck of rain following its peak on Tuesday, according to the National Weather Service.
The cooldown that’s coming will be rapid and significant.
“We have a low-pressure system coming into the West Coast,” NWS meteorologist Dial Hoang said Tuesday. “That’s gonna start the cooldown process (Wednesday), but when we really feel the impacts of it will be on Thursday and Friday.”
That’s when enough low pressure may build that it could cause very minute amounts of rain to fall, Hoang said. The bulk of that figures to be in Sonoma County, where Hoang said the totals could be in the tenths of inches.
“Once we head south of the Golden Gate Bridge, it really becomes a lot less likely,” Hoang said. “In Oakland and the East Bay, in San Francisco, San Mateo and the South Bay, you might get a few hundredths.”
That will be a switch from a high-pressure warm pattern that’s been building since the weekend along with the temperatures. Temps were in the low and mid-80s on Monday and were expected to peak in the upper 80s in the hottest places Tuesday. The weather service forecast temperatures to reach 88 in Livermore, 87 in Concord and 85 in San Jose. Oakland is expected to peak at 80, San Mateo at 78 and downtown San Francisco at 73.
The low pressure is coming from the Pacific Northwest, according to the weather service, and on a typical path to hit land in the North Bay. That will bring a lowering of temperatures by as much as 10-12 degrees on Wednesday, with possibly another 4-5 degree drop from that by Friday.
“Any rain would be later on Thursday or Friday, and possibly into Saturday morning,” Hoang said. “It’s a typical pattern.”
