As for the "rainy winter", here is the explanations from Wiki's Bay Area climate section. http://bit.ly/hf
Winter storms are typically wet and mild in temperature during this time of year, being caused by cold fronts sweeping the eastern Pacific and often originating in the Gulf of Alaska. During November into mid March, winter storms are usually several days in length, wet and cool, with severely damaging storms rare.
Lastly, this is great article about microclimates of San Francisco Bay Area. I highly recommend reading this article to understand that science behind microclimates.
Weather as varied as the people / Land and fog build summer microclimates
July 09, 2001|By Harold Gilliam, Special to The Chronicle http://articles
Crystal Springs Gap (Wind Tunnel)
Farther south on the Peninsula, the San Andreas Fault cuts through the range, producing the Crystal Springs gap, partly occupied by San Francisco's Crystal Springs reservoirs. The breeze through the gap causes Redwood City to be a bit less warm in summer than it would be minus the gap, and the cooling effect sometimes extends as far south as San Jose.
p.s. According to meteorologist Jan Null of Golden Gate Weather Services—who’s been tracking SF weather patterns for decades, the warmest, sunniest patch of SF theoretically lies in the southern Mission, away from water, hills and wind patterns. “Right around Garfield Square,” he says. Debate over. http://www.7x7.com/arts/7