I will also be on this cruise and am from the West Coast. All I can tell you is what I am planning on. I am thinking that the first couple days out of LA will be coolish and hopefully no storms. The weather should warm up as we get closer to Hawaii. Hawaii itself will be very pleasant (pool weather) weather wise (although there can be some showers at times). Be sure to be on the look out for whales.
We were on this same cruise last January (aboard Crown Princess.)
The weather was quite chilly for the first three days, including a few rain showers. Sweaters or jackets were required to spend any time on deck. Also, the sea was characterized by long swells, which made many passengers seasick (not us.)
Hawaii was cool too, with highs in the mid-70s. You needed a wetsuit to spend any time in the water.
We didn't see another living thing from the time the lights of Ensenada appeared until we reached the Big Island. What an experience!
We had a great time, however, and hope you will too.