What shoul I wear for Cali?

Hi to everyone, I am going to Temecula CA next week, I wil live there for 2 months, maybe a little more, I woudl really appreciate your help if let me know what type of clothes should I wear during this time, I am also planning to visit San Francisco, San Diego and L.A, the best clothing options to go out at night and what to wear in a normal day

Thanks a lot!