Historically, February 5th is the snowiest day of the year in San Francisco and the Bay Area. Of the 11 days when snow has been recorded near sea level in San Francisco, twice before on February 5th. In 1887 and again in 1976. (https://www.ggweather.com/sf/snow.htm)
The event on February 5, 1887, was the snowiest on record with over 3 inches in the downtown area of the City. This is well documented in Mark McLaughlin's wonderful "San Francisco Snowstorms" document (http://thestormking.com/Sierra_Stories/San_Francisco_Snowstorms/san_francisco_snowstorms.html)
And the last time there was an accumulation of snow near sea level in San Francisco was on February 5, 1976, with up to an inch downtown and 5" on Twin Peaks. (Spectacular photograph below: Art Frisch, SF Chronicle),
The forecast conditions for tomorrow, February 5, 2019, do NOT look like a repeat of either one of the previous snow events. But the combination of much colder air moving into the region and continued bands of showers overnight should at least whiten the hills above 2000' and in some areas, especially inland possibly down to into the 1000' to 1500' range.
Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services