There is a 90 percent chance of more rain today, according to the National Weather Service.
The forecast for Menlo Park calls for showers and possibly a thunderstorm before 4 p.m., then a chance of showers and thunderstorms.
The expected high is 60, the forecast says, and some of the storms could produce small hail. Not much rain is expected, however, with new rainfall between a tenth and a quarter of an inch.
A storm over the eastern Pacific Ocean had been predicted to strengthen and bring rain to the North Bay late Saturday, spreading to San Francisco Sunday morning and to Monterey by early Sunday afternoon, according to forecasters.
The storm will bring colder daytime highs to the area Monday and cold temperatures Wednesday morning, NWS forecaster Diana Henderson said.
Daytime temperatures will be in the mid to upper 50s Monday with a gradual warming to the low to mid 60s by Thursday, she said.
Wednesday morning temperatures will be in the mid to upper 40s, she said.
The amount of rain falling could be higher in areas if thunderstorms materialize Monday, forecasters said. The best chance for thunderstorms will be in the North Bay and East Bay, according to forecasters.
Small hail and gusty winds may accompany the thunderstorms, forecasters said.
The expected rain may mix with snow at elevations above 4,500 feet, but forecasters expect no accumulation, according to the National Weather Service.
Forecasters warned boaters, surfers and beach-goers that the weather event will bring rough surf and rip currents to Bay Area waters.