San Jose, CA is pretty bike-friendly. It varies, depending on time and location. My commute between South San Jose and Santa Clara is pretty nice, with an occasional buttwipe to handle.

Spring, Summer, and Fall are all good riding seasons, with low humidity and temps normally in the 60's-80's, and the winter is mild, with realtively low precipitation and mild winds. Honestly, there's no need here for more than a pair of knee warmers, as my warm tights were too much when I rode a few winters ago.