I lived there for twenty years. Since you are already there, you may have encountered what the locals call "May grey" and June gloom." The marine layer chooses these two months to overcast the San Diego shore. It's the same thing that causes fog in the Bay Area over the summer. You may luck out. If you do happen to grey out. You may want to do things inland. The marine layer usually didn't survive much more than ten miles inland. An hour and fifteen minutes north, on the I-15 in the town of Corona, is a wonderful hot springs spa called GLEN IVY it's a wonderful day trip. Southern California's wine country is located in Temecula, about fifteen mins on the way back down the I-15. A great place to stop for dinner. I can't remember the name of the road but your hotel will have information. The first winery on the right hand side has a very nice restaurant. Usually with live entertainment. It's a wonderful way to end a wonderful day.