I wouldn't worry too much about late-season hurricanes. When you're in Hawaii
you can see these coming from a long way off, and decide to head
north or wait. Once you are a couple hundred miles north you're out of reach of these tropical storms.
The more significant issues for heading north are the location and nature of the Pacific High, and the low-pressure systems coming down from the Gulf of Alaska
. We were able to take advantage of one of these lows during our Hawaii - Cape Flattery trip last month (see the VALIS blog for our daily reports), but these lows can also generate really tough conditions. These systems usually get worse during the fall and winter.
The reason that the Transpac, Vic-Maui, Singlehanded Transpac, and Pacific Cup sail in July is that is when the Pacific High usually shifts north and tightens up, making for a good race
to Hawaii. That, and people's summer vacation