I live close to the port and have done this cruise several times. This is a link to a Live review of the 4-day. It was in February so not as warm.
Weather - It depends on when you are traveling. We often get a marine layer here in the South Bay, especially in June. August usually is sunnier, but honestly, the weather can be a crap shoot. Ensenada will be warmer than LA and Catalina. Also, we really enjoy taking a private wine tasting tour in Valle de Guadalupe - 30 minutes outside of Ensenada! It is really great if that is your thing.
Three-day NOS cruise review (with Ensenada wine tasting) last August: