From the National Weather Service, in effect for all Bay Area counties:
Strong early season cold front expected to move across northern and central California tonight and Wednesday…
A strong cold front, especially for early October, will move Across northern and central california tonight and wednesday. A brief period of heavy rain is likely with this front…occurring tonight in the San Francisco Bay area…and on Wednesday morning in the Monterey Bay region.
In addition, locally strong and gusty winds are likely along the front. Thunderstorms are possible in the cold airmass behind the front Wednesday afternoon and evening. Some of these thunderstorms may be accompanied by small hail.
Motorists should be alert for slippery roads due to the first rain of the season along with accumulated oil on the asphalt. Fallen leaves and debris may clog up storm drains and result in localized street flooding. Commute issues are likely to occur. Drivers are urged to use caution and anticipate longer driving times. In addition, persons with travel plans to the Sierra this week should plan for winter weather conditions. Carry chains if your plans include traveling over the Sierra passes.
A dry and mild airmass will settle over all of northern and central California late in the week and into next weekend.
And for Solano County, a wind advisory as well.