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Significant rainfall, below-freezing temps in SF Bay Area forecast

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As December nears, the San Francisco Bay Area is looking at another chance of significant rainfall and gusty conditions, with the possibility of frost and below-freezing temperatures likely in the North Bay and inland valleys. 

“Overall, it’s slightly cooler than normal,” Dalton Behringer, a meteorologist for the National Weather Service, told SFGATE on Sunday morning. Compared to last year, he added, “We’re running five to six degrees below normal for high temperatures for San Francisco.”

Temperatures in Sonoma and Napa counties are forecast to dip toward the upper 20s to low 30s this week. Meanwhile, the Santa Clara Valley is expected to drop to the upper 30s while evening temperatures across the bay shoreline will fall between the upper 30s and low 40s. 

“We don’t want the cold to take people by surprise,” Behringer said. “We’re in the last week of November, so we expect it, but since it is a little below normal and nearing the freezing mark in some locations, don’t let it catch you off guard.” 

The coldest temperatures and chances for frost are most likely on Tuesday and Wednesday mornings, the weather service said. Behringer added that frost is also likely in cities like Concord and Livermore. 

Later in the week, the region will get two shots of rain, with the first arriving Thursday morning into Friday morning, followed by another soaking Saturday morning into Sunday morning. The system is expected to start in the North Bay and will spread southward throughout the region. 

“There’s still a little bit of uncertainty regarding how much we’ll see in specific areas, but what I can say is that upwards of an inch is not out of the question across the board for most people,” Behringer said. “As for now, it looks like a good rainmaker.”

The coastline will also experience particularly breezy conditions on Thursday, with wind speeds reaching up to 35 miles per hour.

“It won’t be anything terribly damaging, from what it looks like at this point, but it definitely could be something where we could see pieces of trees down or light impacts,” Behringer said. 

This forecast, including specific rainfall totals, is subject to change, and people are encouraged to check with the National Weather Service for updates.