From my location in Long Beach, October can still see some warm/hot days (80+) along the coast. Maybe a little cooler to the north but temperatures can invert with northern portion being hotter than the south. Would not expect any rain, and little to no coastal fog that time of year (sunny days). If you hunt on the internet, you can find historic average high and low temps, as well as wind and rain for many cities. Eliminates the subjectivity of what other think is ideal conditions. I will say that the best part of October is traffic is probably at a low ebb that time of year. It can be a good ride; if you do it enjoy.