The part of the Bay Area I live in is Piedmont (next to Oakland) known as the East Bay. We are just across the bay from San Francisco. The temperatures here are generally around 10-15 degrees warmer than San Francisco which is fine with me.
Mark Twain once said the coldest winter he ever spent was a summer in San Francisco. When the fog is covering the city in the summer and it's 60 degrees but feels barely 50 with the wind coming off that cold North Pacific, the sun is usually out in the East Bay and it's in the 70s with a lovely cool breeze.
The micro climates here are unreal. I've driven in the to Bay Area from the East and watched the thermostat on the outside of the car go from over 100 down to 65 degrees in 30 minutes of driving. I guess the coastal hills keep the cooling sea breeze from the inland areas.