The San Francisco Bay and Monterey Bay areas are in for some wet weather that may last through Monday, a National Weather Service forecaster said.
Warm and dry weather Wednesday morning gave way to a 20 percent chance of rain Wednesday afternoon and 50 percent chance early Thursday morning.
The percentage increases to 60 to 90 percent for Saturday and another storm may move through the area Sunday, forecaster Diana Henderson said.
"It's going to be pretty much on the unsettled side the next few days," Henderson said.
Saturday's storm is forecast to be the strongest, with widespread moderate to heavy rainfall and strong southerly winds.
During the next seven days, between 0.1 and 0.25 inches of rain is expected in Palo Alto, 1.65 inches is forecast for San Francisco and 1.64 inches is forecast for San Jose.
The rain on Friday will lead to longer than normal commute times and strong winds could lead to downed trees and power outages, according to the weather service. Urban and small stream flooding is also possible.
Henderson said the El Niño weather pattern, characterized by warmer ocean temperatures that led to large storms, is still delivering rain and a chance still exists that the region could exceed the average amount of rainfall this season. However, so far the total is below average for at least some areas.
The total at San Francisco International Airport is 71 percent of normal, while at Mineta San Jose International Airport, the total is at 81 percent of normal, according to Henderson.
San Francisco city officials will have sandbags available for residents who present identification, Department of Public Works spokeswoman Rachel Gordon said.
Residents can go to the Kansas and Marin streets gate of the operations yard in the Bayview District Monday through Saturday from 8 a.m. to 2 p.m. to get sandbags, the first 10 of which are free.
Public works crews will be clearing debris from storm drains before the storm and tree crews will be ready if large limbs or trees fall.
Public works officials recommend that residents call 311 if they see anything that needs to be tended to before the storm, such as a limb that might come down.