October is still the end of the Pacific hurricaine season, but given that, we had the smoothest crossing ever in September one year. It is luck of the draw in the Pacific...either time could be rough or smooth. You will see more whales in Hawaii in January though.
Not to scare you bout....we just returned from a 12 day from Vancouver to Hawaii last week. The five days at sea ended ok, but the first day was the longest day of my life. It was the first formal night and less than 1/4 of the people showed up. I had heard that the waves at one point were 12 - 15 feet. And again the last days were great and the waves went down considerably. Hope this helps. Like KLD said it is kind of the luck of the draw.