You're right, it will probably be cold, but this is Southern California. It could just as easily be 80 degrees... there's just no way to know.scottfiji:late jan, early feb - wow, that is probably the worst time to go on a multi-day trip. it will be cold, maybe rainy.
As long as the conditions are good enough for the boat to go out, you would have fun. I spent a 2-day on the Peace in 40 degree air, windy and HAILING, and 50 degree water last March, diving wet in a 7mm. I was freezing my ***** off, and had to sit out a dive or two to warm up, but had a GREAT time all the same. Wish I'd had my drysuit then, but I'd go back in the same conditions in a heartbeat. I'd go back in sunny and warm conditions in half a heartbeat.