August, early September are the best time because the weather
to the north of the high is as benign as it's going to get and the water
has had time to warm up so it won't be so damned cold. May through early September is the typical sailing season as the weather is decent just cold in the early months. Having said that, once you are north of the trade wind
belt, you can get hit by bad weather at any time of year. More than one boat
has been abandoned/ gone missing during the summer months.
Before and after those times the low pressure systems march across the North Pacific
in 4-10 day intervals. These lows bring everything from gale to hurricane
force winds making it uncomfortable to say the least. It is not the trade winds you are concerned with, it's these lows that are the danger
. In a typical passage
the chances are good you will get hit at least twice and sometimes more by nasty weather in the off season. Did I mention, it's colder than hell out of season as well.