It depends on where you are in Hawaii. It does not rain every day in Kihei or Lahaina. It may rain every day in Pai`a, though. Sometimes it does get hard, long rains as well. While I was on Maui for two weeks, one day received torrential rain for several hours, and it was cloudy the rest of the day. The entire island was getting rain that day. But most of rain falls on the north and northeast side of Maui.