I am also a native southern Californian, and it is very true that the weather is very hard to judge that time of year. We were on the Pride last March (7th) out of Long Beach, and it was 85 degrees in Long Beach the day we left, however Long Beach tends to be one of the warmer coastal cities in the LA area. The first day at sea was around 70 and it was a little breezy, but did not seem 'cold' to me at all. The second sea day was beautiful and around 75 as we cruised past Cabo on our way to PV. PV, Matzl, and Cabo were perfect around 80. The last day at sea was probably the coolest, somewhere in the mid 60's. The ship is pushing against the current on the way back to Long Beach and the ship is probably moving the fastest of the entire cruise. But the center pool has the wind shield and so even on the coolest day we were able to sit out.
Overall we thought that the weather was great, and it was so nice in all of the ports.
Hope this helps!