Atmospheric river to bring 7 straight days of rain to SF Bay Area

Rain is expected to arrive in the Bay Area on Thursday. Once it starts, the region won’t see dry weather for at least a week, according to the latest forecast from the National Weather Service. 

“There is certainty that it is going to rain for the next seven days and likely into the Christmas holiday and beyond,” according to the weather service’s Thursday forecast discussion. 

The precipitation is thanks to a cold front that will likely bring showers first to the North Bay and then other parts of the Bay Area, including San Francisco and the East Bay on Friday into Saturday. That relatively light storm is forecast to drop about 0.5 to 1 inch of rain in the North Bay and up to half an inch in San Francisco, with lower totals elsewhere in the region through Friday. 

But that initial storm system is just a preview of a more intense weather pattern that is likely to arrive on Sunday, thanks to an atmospheric river that is expected to dump inches of water across parts of the Bay Area. 

“Things begin to pick up, basically, late Saturday night into early Sunday morning, and the rainfall begins to intensify again,” Joe Merchant, a meteorologist with the weather service, told SFGATE. 

From Saturday to Monday evening, heavy rain is forecast to fall across much of the Bay Area. Santa Rosa and other parts of the North Bay could see 3 to 4 inches of precipitation, with some areas at higher elevation getting closer to 5 inches. San Francisco could see about 2 to 3 inches during that time, with the East Bay seeing around 1.5 to 2 inches. The South Bay, including San Jose, is forecast to see 1 to 1.5 inches. 

“Not everybody’s going to get rain all the time, all day,” Merchant said of the upcoming rainy weather. “But yes, we are entering a very wet pattern.”

Another system is forecast to pop up on Tuesday, this time coming from the south, but it’s unclear how intense that system will be. Bay Area residents are advised to tie down any loose objects, such as holiday inflatables, and take time to clean out gutters and drains to avoid flooding.