No, Stockton is in the Central Valley between Modesto and Sacramento. I can see where there might be some confusion though. It is at the beginning of the delta which ultimately ends up in San Francisco Bay and many people who work in the East Bay live in the Stockton area and commute an hour or two over the coastal mountains each day. But geographically, climate wise, and culture wise it is definitely a Central Valley city.
stockton, and it s sister city, fresno, are the twin jewels california s central valley crown.it s not considered to be part of the san francisco bay area, as it s over 100 miles away, but it s still closer to SF than to LA.