Average temps here at that time of year are maybe low 70,s in the day and can get as low as 40 at night. As soon as the sun goes down the temp starts to drop rapidly, and mornings are very cool, because of the shorter hours of daylight. If we do have the el nino it may rain.
you can go anywhere here in jeans. One sees all kinds of attire. some wear sandals all year round, and even shorts, but usually in November and December not so much as they are our coldest months. Also it is colder by the ocean than inland, so if you are going to be cl0ser to the beach areas it will be cooler.