The first storm, which is on track to hit the Bay Area late Wednesday morning and last into Thursday, could bring between a half-inch to an inch of rain to communities around the Bay Area, forecaster Matt Mehle said.
Inland hills and coastal mountains could see up to two inches of rain and a chance of thunderstorms is predicted for the entire region starting Wednesday afternoon.
After a brief respite of dry weather on Thursday, a second and stronger system is forecast to arrive on Friday morning and last into early Saturday, Mehle said.
Strong winds are likely throughout the day on Friday and moderate to heavy rainfall could drop between a half-inch and two inches of precipitation in various locations around the Bay Area, Mehle said.
Though the weather service had not issued any weather advisories or warnings as of Tuesday morning, forecasters said downed trees and areas of localized flooding are likely to occur during the change in weather.
By Sunday, rainfall for most of the Bay Area is likely to add up to two to three inches, with pockets of up to five inches in some locations, Mehle said.
The downpour is not likely to change the current drought conditions persisting in the Bay Area and throughout California, according to Mehle.
San Francisco is currently at 27 percent of average rainfall for the season, he said.