Light rain was expected to begin falling Tuesday evening in the North Bay before spreading south through the rest of the Bay Area overnight, National Weather Service officials said.
The rainfall may be more moderate in the coastal ranges, forecasters said.
Most urban areas will receive less than a tenth of an inch of rain, with isolated areas receiving up to a quarter-inch, especially in the coastal and North Bay mountains, according to the weather service.
Breezy and locally gusty conditions will also occur in the wake of the rain. Weather service officials said gusts will range from 30 to 40 mph, mainly along mountain ridges.
Conditions in the region on Wednesday will be dry and that may persist through Christmas Day.
Temperatures will be cooler starting Wednesday night through Thursday morning, with many locations dropping into the mid 30s, meteorologist Roger Gass said.