It should be shorts weather during the day, and it CAN be really hot and dry (in the high 90s) if we get a "Santa Ana" weather condition. San Diego and Oceanside will be cooler than Anaheim (since they are along the coast), and you will definitely want a sweatshirt and maybe even long pants at night, since in the coastal areas you'll have temps in the 60s and high humidity, and it gets chilly.