The Best Times to Visit Hawaii: 2
Hawaii also tends to be very busy throughout June, July, and August. It is hot, it is humid, and since school is out for the summer, it can get tremendously crowded. The end of April and beginning of May is not much better, because it marks the Golden Week holiday in Japan.
As well, hurricane season begins in June and ends in November, so you definitely want to think about avoiding the islands then, just to be safe.
If you are looking to experiencing good surfing in Hawaii, however, then winter is a good time. The waves are not great during the summer, but they get killer during the winter months.